My Boat Videos - Gotta Love the 351
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URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=6131
Printed Date: April-28-2024 at 5:42am
Topic: My Boat Videos - Gotta Love the 351
Posted By: 64X55
Subject: My Boat Videos - Gotta Love the 351
Date Posted: March-27-2007 at 10:17pm
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Hey guys -
Just thought I'd post links to these 2 videos of my boat I posted on You Tube. Besides my project inboard (the '64 Dunphy X55 with Correct Craft windshield and Trailer), my other boat is a 1969 Cobalt XV-200 which was an exact copy of the Donzi Ski Sporter or "Sweet 16." The 2 videos are short, but I thought they were pretty cool and all you 351 Ford fans will like the sound! A bit louder than inboards due to the above the water exhaust and lack of exhaust hose length (since the engine is right at the transom). The manifolds, marinization, etc. is Holman Moody. To my surprise the video does the sound justice pretty well. It was from a Canon Powershot A540 digital camera. Heres the links: http://www.youtube.com/watch?v=qWb5d8va35M - http://www.youtube.com/watch?v=qWb5d8va35M and: http://www.youtube.com/watch?v=s1HW5lWLjEI - http://www.youtube.com/watch?v=s1HW5lWLjEI Enjoy! ------------- Inboards Rule! |
Replies:
Posted By: reidp
Date Posted: March-27-2007 at 10:55pm
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Thanks Craig, as I certainly enjoyed it, about 10 times. And I never knew Cobalt built a boat like that back in the day, and I'm a big vintage Donzi fan next to Correct Crafts. We've certainly have a lot of their more modern boats around here. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: MaddMarxx
Date Posted: March-28-2007 at 12:42am
| Cool videos...That does look like a sweet-16, that has a 351 in it? How fast will it go? |
Posted By: 64X55
Date Posted: March-28-2007 at 6:58am
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Mid fifties with my current 14x23 aluminum prop. Used to have a 27" pitch aluminum prop that would get it to 57 mph. Lost that prop!
I have since bought a stainless and have never tried it yet because I have to make a slight alteration to my prop shaft (drill a hole) that many guys have done (and tell me it's no big deal) but I'm a little afraid of doing it. I will eventually, just want to be sure I don't mess anything up! ------------- Inboards Rule! |
Posted By: 8122pbrainard
Date Posted: March-28-2007 at 8:09am
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65X, Tell RiedP about the law suit that Donzi had against Cobalt for copying their 16'. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 64X55
Date Posted: March-28-2007 at 9:36am
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Oh - yes, "the rest of the story" -- Donzi never okayed the use of their molds (for Cobalt back in 1968). As a result there was a court case that halted production of these first Cobalts. Consequently, according to the company (Cobalt), there were only about 40 of the XV-200's ever made. They popped two other molds as well; a copy of the 18' Donzi Corsican which Cobalt called a GT-500 and a copy of the Donzi 18-2+3, they called a Cobalt XV-200. I've located a good handful of the 40 XV-200's (less than a dozen), less of the GT-500's (maybe three) and the only indication of an XV-500 actually making it to production is a page from a brochure (from I think 1970) that shows a photo of one. I've not been able in 22 years of looking, to locate an actual XV-500. In fact, I was convinced none existed until this past year when I obtained this catalog page with an actual photo. I knew about them from an earlier catalog (probably only one year earlier) that was entirely artist conceptions of the models. Very detailed colored pictures, but not photos, so I couldn't be sure of a model's actual existence until I found a "real one." In the old art drawn Cobalt catalog one other Donzi was slated for copying as well, the Donzi 7 Meter (Cobalt was calling the "Cobalt 23" - how creative) and a Cobalt "semi-copy" a 16' version of the Donzi Corsican 18. I say "semi-copy" because Donzi never made a 16' Corsican.
Oh 8122, look at all that rambling you instigated! My wife and kids dread when someone asks me about my Cobalt! They usually say something like "Oh no, here we go again!" ------------- Inboards Rule! |
Posted By: Riley
Date Posted: March-28-2007 at 10:51am
| I never knew Cobalt made boats like that. A Ford IO is pretty rare, too. What kind of outdrive does it have? |
Posted By: 64X55
Date Posted: March-28-2007 at 1:04pm
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It's a Volvo AQ drive. The Cobalt's are just like the Donzi's with regard to all that. They used mostly Holman Moody, but also some Interceptors and Chris Craft (engines) that were mostly hooked to Volvos (also some Mercruisers) in the old days. Later used OMC's for a while then almost all Mercs. Did all models with an occassional V-drive option.
Most of the Donzi and probably all of the Cobalts that were IO (most were) had 289, 302 or 351 Fords through the 60's and 70's. And the outdrives were mostly Volvo's (AQ-200, 250, 270, 280's - lots of those models through that period) as well as Eaton (earlier on). My '69 came with a 250, but I've upgraded it to a 280 (just because the 250 was getting worn and I found a deal on a 280). A lot of those drives had interchangable components - you could mix and match parts a little. For instance, my old mounting collar was in better shape than the one I got with the newer 280, so I used it. The 280 bolted right in (so to speak). Ford was really common enough with IO's in a lot of boats until more recent years. Even in the 90's OMC used Fords a good bit - a lot of the 90's OMC Cobra outdrives had Ford engines. Seems like the inboard ski boats are the only ones who had kept on commonly using Ford V8's after a point in the not too distant past. I've heard that skiers liked them for their good low end torque (just repeating some hear-say). I think Ford is almost completely out of most marine stuff now. ------------- Inboards Rule! |
Posted By: reidp
Date Posted: March-28-2007 at 1:20pm
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Preach on, Brother X: I could read this kind of valuable info for hours. But rest easy, as I easily out-ramble you I'm afraid. Thanks Pete for egging him on. I'd like to see some more up-close boat and engine picts if you have them.
Riley, lots of Ford powered I/Os up thru late 70s and probably a dominant number. MerCruiser even used Fords for quite a spell along side the GMs. Still a handfull of Volvo and OMC Fords up thru mid-90s. Hard to find an early orig Donzi with anything but. EDIT: Disregard most as Craig beat me to it above. Holman Moody actually marketed the Volvo unit with their own name on it, HM that is. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: reidp
Date Posted: March-28-2007 at 1:37pm
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Craig, When you get a chance I'd like to speak with you regarding the Volvo 250 drive. We've got a '67 Donzi 18' we're working on with one and as you realize, you couldn't trim them, so even running in the highest tilt-pin hole it's not enough trim. Can you get a trim kit for the 250 or is the best bet to go with a 280. The tilt on the 250 drive works great, just no trim-action (story of my life). I'm an inboard guy by nature but these old Donzis/COBALTS are nice and I just don't know squat about the drives. I'll try to get some picts posted of this 18 we have, plus my business partner has a '92 Sweet 16 with a 302 Ford OMC which I've posted picts of before I think. Here's another of it at crystal clear Silver Glen Springs off the St Johns River in FLA, sitting between two Mustangs, while we were down for the Orlando Reunion bout 2-3 years ago. Met jbear there.
Thanks, Reid 704-451-5080  ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: 64X55
Date Posted: March-28-2007 at 1:49pm
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Yep, my Volvo drive has a plate that says Holman Moody Marine where the plate would normally be the model number plate that many will remember (270, 280, etc.) being used probably into the late 80's.
I've got way too many pics. I gotta get around to checking into the photobucket thing to post some pics. Forgot to mention, reidp, you're right; there were Mercruisers with Fords too in a few of the Donzi's I've seen; 302's for sure. (mostly at a (I guess, "the") Donzi website - not the official Donzi company one). Those made a fast little set up because they had a gear ratio of 1.5:1 vs typical Volvo of 1.61:1. Makes a pretty good difference! It is funny; when you think Mercruiser, you're usually thinking Chevy, but it wasn't always that way. Oh, there were also some Jet drive options (with classic Donzi's)and even Chrysler marine engine options. The Donzi 16 was even offered with outboard power - called a Baby Donzi. They're neat little boats and quite rare I believe. ------------- Inboards Rule! |
Posted By: 64X55
Date Posted: March-28-2007 at 7:11pm
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reidp,
There was a 270 that had a trim option (called a 270T) but as I recall the mechanism for it wasn't great. I think partly because it was a single piston affair (I forget exactly). Even my 280, like the 250 has only the electric tilt motor. The 280, I'm most certain "could" have power trim, though, as I said, mine doesn't. And then the 290 (which I haven't mentioned) did have power trim (I think always). The 290 is less interchangeable than the 280's on down because it's mounting collar was significantly different. I'm surprised at what you said about "not enough" trim on even on the third (highest) pin. I think it has a significant amount to do with the prop (some will lift the bow a lot more than others), but many of these boats up on the 3rd pin get real squirrely on the third pin indicating maybe too much trim. (I may be thinking more of my experience and what others have told me with the 16's, the 18's being a little different - better in a way due to the added length). "Trimless" is just a bit of a pain because w/o the adjustability while running that power trim gives, you have to settle for either good handling and lower top end speed, or good (but often hard to control) top end speed and too much bow rise on take off + porpoising in the mid range! One good thing is that most if these little boats can hit the low to mid 50's even on the lowest pin setting (where you also have good control). That is to say, even the slowest setting isn't really "slow!" Still, power trim certainly makes the boat more versitile. Because the huge majority of these boats are stern drives, and many still going are from the 60's and 70's, the guys on the Donzi web site have had numerous posts, pictures and advice about how to tweak, what will match what, etc., etc. (data piling up there since I think 1998). They could give more info. of a "most economical" way to get the boat set up with trim perhaps retrofitting parts of what's on there now. I don't think there's a good option to achieve having power trim with the 250 drive though. If you like Donzi's, you ought to check the site out anyway. It's similar to this site, but with Donzi's! I like the picture you posted. Wow, I love Mustangs too. It's a Donzi/Mustang sandwich! ------------- Inboards Rule! |
Posted By: reidp
Date Posted: March-28-2007 at 7:39pm
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Thanks for the feed back Craig. In regards to the trim and manual placement on the highest pin, this boat surprisingly doesn't porpoise even at mid throttle. The prop will catch air in slow hard turns. The prop by the way is an original style, large blade aluminum. I don't even know where to start to find a stainless perf type. We only picked up the boat in October, replaced the dead engine with a stout alum head 302, and here we are. At higher speeds with a low pin setting the boat will grab the starboard chine and jerk suddengly in that direction and lean, but won't do this with a higher/higheest pin setting. Also, at the highest pin setting you get no cavitation/ventilation whatsoever. This boat by the way, came with a 289 Interceptor. The 16' with trim, conversely will porpoise anytime at low to mid-throttle unless the drive is almost all the way in. A completely differently set of manners from the 18. Headed out of town tomorrow for a few days of business and away from computer. Thanks again and we'll catch up later. Sorry everyone else for the boring non-CC babble. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: scott8370
Date Posted: March-29-2007 at 12:35am
This is the second post in weeks, that Donzi has been talked about with pictures included. I just love their looks and been looking at them on ebay, boat trader....I would love to have one someday. I looked at a 1995 with a 502/ bravo drive set up..Holly sh*t!! And a 1994 40yr. anniversary with a hull #001 for $35,000.  ------------- Scott |
Posted By: 64X55
Date Posted: March-29-2007 at 7:50am
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Reid, Interesting about the pin settings. My brain is more tuned to a 16 and you're right the 16 behaves well with the pin on the low setting. I haven't heard from anyone that the almost total opposite occurs with the 18 with regard to the pin setting and how the boat behaves, but that's interesting. I think part of it may be that, as you've said, you've been mostly an inboard guy. The extreme deep V of the 16 and 18 Donzi does tend to shock people at first in hard turns who have been in other boats a lot. I'd say probably "especially" inboards because their degree of deadrise is so slight (many with nearly flat bottoms).
That is how these boats handle. I think it's fun, but you definitely gotta get used to it. Of course the big plus to that extreme V is that you can blast into big waves at high speed and fly without fear of being severly pounded upon landing. In fact, that's the other "surprise" with the handling of these boats. When you do that every "new" passenger grabs a rail and grits their teeth... 
Then the boat lands with amazing smoothness and your passenger says "What happened? Why doesn't my spine hurt?"
The down side is that while they have enough HP to take off quick, the extreme V makes it hard to maintain nice slow skiing speeds for things like tricks and wakeboards. The wake is big at those speeds, but hard to maintain. Plenty of speed for barefooting! I barefoot ski with my Cobalt at nearly wide open, of course the mid 50's speed gets reduced some by the drag (so I'm probably barefooting at high 40's - but I weigh (I think) 225-230? (I've lost track  ). The porpoising can be a little bit of a problem. My wife doesn't like driving it when it does that and, getting up to speed to step off a slalom ski to barefoot, it does tend to hop some.------------- Inboards Rule! |
Posted By: Luchog
Date Posted: November-10-2007 at 1:09am
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Reidp, I had a boat with a volvo 280, try different style props, they are night and day, each prop gives the hull a different planning angle amd height, then you set the pin position if the prop ends too deep or too shallow into water by checking wich side the wheel turns when you let it go. You should be able to let it go and have the boat making a straight line.
In my experience the "high speed" propellers are better for pulling, they have the hull plough into water and need a lower pin position. turns are not that great and neither is gas milleage A "michigan" blade style prop took the hull out of the water, helped a lot on tracking and turning, improved gas milleage and needed an upper pin position. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: jbear
Date Posted: November-10-2007 at 1:37am
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ReidP; Biggest "thrill" of my summer? Driving that cool Donzi back down the lake in the early morning (Saturday) during our visit. Think we were coming back from chasing down the guys taking a boat to breakfast. All I know is it was fast!
john ------------- "Loud pipes save lives" AdamT sez "I'm Canadian and a beaver lover myself"... |
Posted By: reidp
Date Posted: November-10-2007 at 11:14am
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I've finally got an update to our prop woes of last spring and summer with this '67 Donzi 18. I feel like I have a pretty decent handle on props for various vintage CC setups, but I've been clueless on the old Donzi's or I/Os in general. I ran in to a prop expert on the Donzi site who hooked me up with a "Solas" prop which he helped them develop for these old drive combos. Anyway since this summer we replaced the oil-leaking, std rot spinning but rev rot-sealed temporary engine with a 347 stroker which used the same alum headds/intake etc that were on the 302. It turned the alum prop up to 57-5800 so I knew that wasn't gonna last, and only 57 mph to boot. I got the only size Solas prop he had at the time which is a 15-5/8x23 (this thing is HUGE)and barely fits, and this dropped the rpm all the way down to 46-4700 but raised the speed up to 60.6.
Sidenote: I'd never had the GPS on it before with the 302 and had only run it beside my buddies Checkmate and was told we were running 59 which turned out to be something like maybe 55. But back to the new prop, I'm sending it back for a 21" which will get the rpms up toward the 5000 area where this particular engine wants to be and will hopefully get the 2-4 mph that this boat will supposedly run with 330-350 HP. The guy I bought the prop from told me specifically that if I indeed had the 350 hp that the desk-top dyno program indicated, that I would be able to turn the prop up to about 4600. He knows his stuff. I've learned recently that prop changes on these boats have a more profound affect on speeds and handling characteristics than they do on our CC boats. This boat has hydralic steering which limits the annoying torque-steer these boats commonly exhibit at various speeds which Lucdog was referring to. Food for thought: Just yesterday evening while headed home I was trying to decide what actual boat or "type" of boat was the most fun or biggest rush to drive. Is it a flat bottom ski boat that accelerates like a rocket and handles like a sports car, but may beat your brains out, or a deep-vee that runs fast and cuts thru the harsh chop like butter, or a vee bottom inboard or just what? Well, to me it quickly summed up this way: I can always pick a time when the water is flat, but I can't make a deep vee handle or do what the little inboard can no matter what the conditions are. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: 64X55
Date Posted: November-10-2007 at 4:59pm
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Reid,
Sounds like your expanding your knowledge of props into the realm of stern drives. Interesting stuff, aint it? 
I didn't even pop over to the Donzi site to check, but I'll bet you were talking to Randy ("Big Grizzly" on the Donzi site). Am I right? I'd say he's the guru over there. He's very knowledgeable about the props and I'm most certain I read (probably over a year ago) the stuff about him working with Solas. Pretty neat info. Randy has at least two "way cool" Donzi's, a (I think late 60's or early 70's) Inca Gold 16' Donzi with a Grumble Green stripe and interior, as well as an old 18' Corsican which is very sweet. I believe the 16 has a Mercruiser outdrive which was less common than the Volvos in that era, but because of the "better" gear ratio, it's pretty quick (well over 60 mph as I recall - maybe even 65 and that's screaming in 16' Donzi). His Corsican has a Volvo drive I believe and is probably the boat he did a lot of the Solas prop testing in. I was able to find a new Michigan Wheel stainless 14x21 cupped prop for my Cobalt (same as the Donzi 16 and the boat in the video links at the beginning of this thread) but I've never tried it yet (2 yrs now) because my Volvo 280 drive is one of the ones that didn't have the threaded hole in the tip of the prop shaft. I haven't gotten into that project. The guys on the Donzi site assured me that it's no big deal but I'm a little reluctant to rush into it. I'll do it some time! The current prop runs the boat well in the mean time. It is a 14x23 aluminum Michigan cupped prop. It turns the engine at around 4400 rpms and the boat is hitting low to mid 50's (like 54). Lately it's even been a little slower. Haven't changed plugs, etc in a while. And I always use 87 octane. Just those two things might improve matters a bit (at least back to 54 mph). My goal with the 21 stainless is to hopefully get the rpms up to 4600-4800 range (which is recommended for my 351 Ford), in hopes that it might increase speed a tad. So many factors. It would at first seem that the increase in rpms might slow the boat down, but my hope is that the stainless will experience less slippage and therefore raise the speed a bit with the increased rpm's. Won't know til I try! Something to look forward to! You can go through the little prop pitch vs rpms vs Gear Ratio = theoretical speed (allowing adjustments to the theoretical pitch change due to cupping) and then, based on how fast the boat does end up going on the GPS or a good gage (vs theoretical speed), calculate the amount of slip. It seems the aluminum props I've tried are always in the high teens (percentage wise) for slippage and the guys with stainless often get less slip. I won't be getting much above high 50's (I don't think) any way you look at it because my HP is at 290 (and I believe that's rounded up). I have the old engine (needs rebuilt) that was rated at 290 and it was definitely stronger, but my current engine is a newer PCM crate motor disguised as the original Homlan Moody 351/290 hp (for the proper look). In the small print, of my paper work for this newer crate motor, I noticed it said 285hp in really small print so that's why I say it's rounded up. The old engine would turn a massive Michigan Wheel 14X27" aluminum prop at 4600-4700 rpms and do a solid 57mph! That's pretty quick for any aluminum prop. And in the 16' Cobalt it was a blast. Still exciting but not quite as much. Hard to lose any top end after a bunch of work! But, being newer, it's been very dependable and it's really plenty fast. Yeah, it's fun to fiddle with this stuff. As far as what's more fun (a deep V that slices through big ole' waves easily while the ole' speedo is dancing around the mid 50's, or turning on a dime so fast you can break your ribs (right Pete?) in a nice inboard on a smooth day?), --- that's a tough one for me. Almost like the chicken or the egg thing. As I slowly (very slowly) get my old inboard together, I'm looking forward with anticipation to having the same tough decisions to make! 
Actually this particular old inboard isn't going to be able to do the fast turns (apparently due to it's design), but if I get it back to where it's suppose to be, it will be able to hit the mid 50's in smooth water! Pretty good for a 17' inboard built in 1964! I can't wait! ------------- Inboards Rule! |
Posted By: reidp
Date Posted: November-12-2007 at 12:00pm
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Nail on the head, Craig, as it was Randy/Big Grizzly. Nice info you posted as usual. I'll bring it back up some time here soon as I progress with another prop. Big day this morning so I've got to jump in. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: 64X55
Date Posted: November-12-2007 at 2:36pm
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Might be jumping ahead here, but found some good info. in my February 2006 Boating World on props; a neat piece from the Q&A section with a bunch of prop info.
It says (and I knew some of this) that the rule of thumb is that by adding an inch of pitch, you'll decrease rpm's by 200 to 300 (and of course the opposite would be true - subtract an inch to gain 200-300 rpm's). Also says (something I didn't know) that the tendency, by going from aluminum to stainless, is that you will also experience some (amount not stated) reduction in rpms's. And finally, that, as a rule, stainless props give better bow lift on heavier boats, resulting in better performance. And I think, just my observation, when people, speaking about props, say "performance" they're talking mostly about speed (unless the say something like "all around" performance). So, applying all of this to my scenerio (my Cobalt - (same should apply closely to a 16' Donzi and loosely to an 18' Donzi)) it seems that if I start with what I am observing now (4400 rpms at WOT hitting 54mph with the 14x23 cupped aluminum prop. and my 1.61:1 gear ratio (GR) for the Volvo 280), I should be able to predict what the 14x21 cupped stainless will do (with an assumption about HOPEFULLY improved slippage thrown in). I plugged in the numbers and, since I know the speed with the 23 alum. I can calculate the percentage of slippage it's experiencing. I did that and have estimated that it is experiencing about 10.23% slip (if I'm doing this right). Theoretical speed, considering the 4400 WOT rpm's, 23" ptich, and 1.61:1 GR would be 59.52 but she's only actually running about 54 mph. 954/59.52=1.1023). Assuming I'd get the same slippage with the 21" stainless - it worked out to a theoretical speed (not adjusting for slip) of 60.52 mph. Apply the same 10.32% slip factor and I got an calculated speed of 54.90 mph with the stainless. This was taking into account that the 2" reduced pitch takes the rpms (up 400 to 600) from 4400 to 5000 (on the high side I know; I was being a little optimistic here)and then also the "change to stainless" effect, I estimated would drop the rpm's say 100 (?) to 4900. I felt that these seemed like reasonable possibilites based on all this jiberish! So 54.0 mph to 54.9 mph? Hmmmm? Not a whole lot better. BUT, if the slippage is decreased, and I'm guessing that that will be the case, based on the fact that a big reason stainless gives improved performance is that it doesn't flex as much as aluminum, I can calculate various reductions in slippage like so: At 2% less slip than the alum., theoret. speed = 60.52 mph / slip (1.0823) = 55.92 mph. At 3% less slip than the alum., theoret. speed = 60.52 mph / slip (1.0723) = 56.44 mph. (Skip 4% less) (it came to 56.97 mph) At 5% less slip than the alum., theoret. speed = 60.52 mph / slip (1.0523) = 57.51 mph. Hey, I'd be happy with that because that's how fast she went (actualy 1/2 mph faster) with the old engine and the big ole' 27" pitch prop! The up side to it all is that the 21" would be able to hold slower speeds better than the 27" ever could making it possible to pull wake boarding kids (as well as occassional 45 yr. old wakeboarders that need to go on a diet and take better care of their backs). The old 14x27" was not so good for that (as you can imagine). I once told a prop shop repair guy that I used the boat for skiing (with that 14x27 prop)and he said something like "That's like trying to pull a Winnebago with a Volkswagon!!!!!!!!!!!!!! So what does all this aluminum vs stainless prop junk have to do with a bunch of guys that all (98%) have NiBrAl (or bronze?) props under their boats? I'm not sure! I just started typing and couldn't stop! 
------------- Inboards Rule! |
Posted By: JoeinNY
Date Posted: November-12-2007 at 2:56pm
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I am not sure either but I do think some of us should be running stainless props. They are not a miracle but my outboard experience has always been that they are good for about 1-2 mph on the top end at the same rpm. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: 8122pbrainard
Date Posted: November-12-2007 at 7:02pm
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Craig, Our host's server is running out of memory!!! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 64X55
Date Posted: November-12-2007 at 8:31pm
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I thought I might get some kidding (Pete!!) about rambling on like that!
I think "JoeinNY" summed up, in about 2 lines, what I took "two whole rolls of the mouse wheel" to say! (except, technically, I was describing a 3.5 mph speed increase!
It's funny, I see stainless props available for inboards in Overton's, etc. but I don't hear much talk about them. I would guess there are similar advantages for inboards just like outboards and sterndrives. Maybe, as Ried, I think pointed out above, there is less to gain with stainless on inboards. Hardly with the $300.00 to $400.00 price if it's not going to do something noticeable! I don't think I know anyone personally that has an inboard with a stainless. I'm sure some on the site do, right? I'm guessing this has probably been talked over already. ------------- Inboards Rule! |
Posted By: Riley
Date Posted: November-12-2007 at 8:56pm
| I don't know about Correct Craft, but Malibu and MC was using SS props in the late 90's. IIRC, they were made by CVC. They offered improved performance at the time, but the Acme and OJ CNC props are even better. Two big drawbacks with SS was some got stress cracks and shed blades, and if you hit something, you did far more damage to the drive train. |
Posted By: 64X55
Date Posted: November-14-2007 at 11:54am
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Yes! Forgot to touch on that. That's probably the main reason you hear (other than cost) that aluminum is a good idea for many applications.
With the stern drive props, there's often (maybe always?) a pressed in rubber hub. Some in the past (I think at the Donzi site) had discussed props that didn't have it (mostly like bronze props that were altered to exclude it I think - because they'd "spin" too easily (meaning the hub rubber)), BUT if you bumped those fixed hub jobs very hard you might really mess up your outdrive. Seems like fisherman (with mostly outboards) would lean toward aluminum for that reason -- running in shallows a lot, etc. Ski boat owners, you would think, might avoid shallow water in general, but then again, looking for the smooth water, many skiers gravitate to rivers (generally smoother water) that have a higher amount of sumbmerged "floaties." Lots of things to consider. For an inboard, I think I'd just stick with the non-stainless unless I was pretty sure of the water depth and the debris you might encounter. ------------- Inboards Rule! |
Posted By: eric lavine
Date Posted: November-14-2007 at 4:22pm
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with the aluminums, i had a guy that his boat took forever to get up, he wanted prices on rebuilding his engines. the strange thing was he was getting 200 more RPM's at w.o.t, He was a friend so i suggested some new props first, it cured the problem, the boat had alot of hours and what was happening was the blades were flexing straight and not allowing the boat to pop up, the aluminums do wear as in this case ------------- "the things you own will start to own you" |
Posted By: JoeinNY
Date Posted: November-14-2007 at 5:02pm
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IMHO aluminum props don't belong on any boat that you care about the performance of, I them on old outboards under 50hp thats it. I am still on the fence about bronze and nibral props. I have an old 2 blade bronze prop that fits my inline 6 mercs that spun the hub without putting a nick in the prop. My two modern Nibral props that made momentary idle speed ground contact were both declared unrepairable by the manufacturer (one OJ one Acme) in similar situations with stainless props I would have expected no damage. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: reidp
Date Posted: November-15-2007 at 12:48am
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First off, Craig, you can NEVER write too much, so don't apologize. They just don't have to read it, or can skip thru it if they're not interested. But I know a few of us anyway are certainly interested.
As far as stainless on inboards, I've got one of them (12x13 OJ) running right now on my blue Mustang and I think it's fine, but I can't tell that it's any faster than the same size OJ I also ran/run in Nibral. I couldn't see the SS's being that big of an improvement mainly because I feel Nibral is such a good material, and while not as strong as SS, it surely gets cast to as fine and sharp an edge as any SS, which is a far cry from alum, which is never cast with a sharp edge on the leading or trailing side. Eric Johnson at OJ told me the SS wouldn't flex as much as nibral and theoretically could be faster than nibral with all things equal. That stainless sho is purty though. Joe, on the question of damaging the SS's, they will certainly fold a blade just like the others, but maybe not as easily. So I don't know that you'd have escaped unscathed after solid contact. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: 8122pbrainard
Date Posted: November-15-2007 at 8:33am
Reid, Craig emailed me a couple years ago when he was thinking about buying his X55. Ever since we have been emailing each other on a regular basis talking about the restoration of his X55 ,boats and just things in general. I have learned that Craig can get "windy" at times so I was just working him over a little!! He's real big on the prop calculations. The other day he did one on "Miss X 55" which is one that the owner has done some 312 engine mods on and claims to do over 60. Craig figured with normal slip and the prop the owner is claiming that the engine would need to be cranking at about 5000. Note: Tim, I did the double quote!! You'll turn me into a computer geek one of these days!! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
8122pbrainard wrote:Posted By: reidp
Date Posted: November-15-2007 at 1:09pm
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Pete, I thought your comment was classic and I know you and Craig are pals. I think indirectly I was probably justifying my own longwindedness (is that a word?) and looking for company in Craig, since I'll give anyone a run when it comes to babbling on.
I fortunately or unfortunately share Craig's interest in the prop calc's but they continuously stymie me and mostly in the area of slip. I just keep playing with the numbers and along the way you learn prop sizes/results, engine power and speed as a function of rpms, etc., all the stuff a gear head or speed freak likes to know. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: Luchog
Date Posted: November-15-2007 at 1:24pm
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Reidp I have a propeller topic going on on General&stuff regarding a prop for my 80' SN, I'd not make such a large debate about a prop and buy a few and test them but since I'm 20k miles and each prop cost a little fortune to my economy I need to do all my homework before getting one.
would you mind giving me some input?? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: 8122pbrainard
Date Posted: November-15-2007 at 1:31pm
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Luciano, Tim (TRBeng) was doing a big summer test on props. Tim, Did you ever finish the prop testing and compile the results? The slip results should be very interesting because it is the big vaiable!! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: TRBenj
Date Posted: November-15-2007 at 2:17pm
Prop testing is finished and I have a bunch of numbers. I havent crunched them yet, but have a pretty good feel for what I would recommend on all the 1.23 direct drive boats. There isnt a whole lot that would help all the 1:1 guys, as I was dealing with a totally different set of props. I will be putting together the full writeup and having Keith post it. Its on the to-do list. ------------- |
Posted By: M3Fan
Date Posted: November-15-2007 at 4:53pm
Is it the same thing you've always recommended for the 1:23 boats? Any surprises? ------------- 2000 SN GT40 w/99 Graphics/Gel 2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
Posted By: TRBenj
Date Posted: November-15-2007 at 6:21pm
No real surprises- and Ive been giving advice based on my results for some time. I decided to keep the 612 and 1442 for my boat, as they were the best performers on my hull. The 1442 is the prop I recommend for the pre-TSC boats with the HO motor (the 612 is NLA), as it dials back the RPM a bit compared to the 470. The 470 is my choice on the non-HO motors or heavily weighted boats that benefit from the added RPM's. On the TSC2, the 612 and cupped 470 were my favorites, followed by the 470 and 422. ------------- |
Posted By: 64X55
Date Posted: November-18-2007 at 8:25pm
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Jumping backwards a bit (didn't check in for a while), Thanks Ried and Pete! So it sounds like I've got the green light to ramble on & on & on & on...! Wait, I think I feel a three pager coming on!
Just kidding.
It was interesting what you were mentioning above about the flex factor of the NiBrAl. You usually see a lot of comparing between aluminum and stainless and folks don't mention the NiBrAl a lot. It's like "Oh that's what goes on an inboard" and that's about it. This has been a cool thread with a lot of neat info. I had always noticed the huge differnce in the typical inboard props pitch (as compared to sterndrives and outboards). Didn't know for a long time that most inboards were close to 1:1 ratio. I think I just assumed it (in my ignorance) since the were direct drive and the pitches were so low. Most outdrives ratios are in the 1.5:1 or more (the old Volvos for V8's being largely 1.61:1 and then for 4 cylinder engines, as much as 2:1 and I think even higher). Noticed above the mention of 1.23:1 inboards. Ried; you're right, the main wild variable is the slip factor. It's like that's what you're really calculating if you have known actual speeds, and then theoretical speed, rpm's and gear ratio. It's fun to try to predict the numbers. As mentioned, cup does some things too. Most of my rambling has been from memory from reading, experimenting, and talking to the guys at the Donzi web site. I gotta dig out my old Mercruiser "All you need to know about props" book. It is very cool and full of great info. Wow; that's all I could come up with. I must have web writer's block.  ------------- Inboards Rule! |