How fast is fast?

My 79 Tique (302 Commander) hits 43-44 with a few minor mods. I'm 30 with two kids we ski 80% float some, and cruise a little. Being in the water is where it's at for us. I got a new Acme 542 for x-mas I hoping for more hole shot.

BKH your right about the chop, we always hoped for 2 to 3's in which the boats performed the best. you can even feel this(drag) while waterskiing on a dead calm day, and if you have a little chop you feel alot faster

Eric,i think the word is "Wetted Surface" and Hrydrodynamic Drag, both eat hp at an alarming rate,that is proportional to weight.
After years of racing Hobie Cats,very simple motor,you find that weight and hull drag are our two biggest demons.We are restricted to stock sails and rudders, so all your extra speed has to come from the loss of said "drag"
Nothing slides over water any better than water,Hence one of the bottom paints was Outlawed on our Hobies. The product is called Miracle Micro-Baloons, gives the bottom a look simular to an orange. The golf ball princapal only in smaller scale,but gives the same effect to drastictly reduce drag........boat dr   

I thought donzi was one of the firsts to introduce the stepped hull, I can remember them as far back as 1987, the less boat in the water the faster you go as with the hydro's they have air foils on them that the drive controls, because they glide above the surface, with just prop contact to the water. The orange peel does make good sense and as with air im sure it works with water.
   This is purely recolection so dont take it seriously if you think its wrong

When Dunphy started producing the X55 they got a U.S. patent on it that was called the "balan-stern" stepped hull. There are some drawbacks to the steps. They aren't as manuverable as a flat bottom I think due to the steps dragging in the water on turns. Also all the X55's will ocasionaly at about 7/8 WOT flatten out in a turn to port and go straight!! It can be scarry if you don't know the boat. The theory is that the prop rotation at a certain RPM and the starboard step produces a air pocket so basicly the rudder cavitates. When our ski club had the X55 we had to change the show coarse from counter clockwise to clockwise!! I have installed a slightly larger rudder on mine to eliminate this and I beleave the last production run of the X's had the larger rudders. It's still damn fast!

Reid, The X's would flatten out and go straight after you were into the turn and that's when you usually really needed to turn!!

he told me to use the 540 on mine which was way under proped went with a 470 after finding what the max rpm was first so that I knew exactly how many rpm's to drop down to. With the modes you descriped your going to need a much larger pitch than you currently have.

Guys, I certainly can't claim this as the gospel, but when making mods to an engine that don't involve increased cubic inches, the original sized prop often provides the best performance. An increase in HP doesn't dictate a prop size increase as much as cubic inches and increased low rpm torque do. When you make modifications that result in the capacity to turn higher rpms, you typically also raise the power band and rpm required to demonstrate this new found HP in terms of response and mph. Our main work horse is our 69 Mustang with a multi-staged modified 302/308(.040" over). The original 210HP 302 would spin the original 12x14 prop about 4400 rpm. Step by step we continued to add power until it would eventually turn that same prop 5200. Experimenting with a 1/2 doz props I went up to a 12x15 which dropped the rpm the anticipated 2-300rpm but it also dropped the speed about 1 mph and the holeshot and throttle response were off just a tad. Just for kicks I tried a 12x13 Fed to see if the cam and head combo wanted more rpm, which indeed pushed the rpm to about 5500 and would snap your neck, but it slowed the boat a good 3 mph, basically saying that it pushed it out of its HP making range. So I went back to the 12x14 Fed or more satisfactorily the 12x13 OJ which turns the same RPM. (Note: an OJ prop because of the positive, aft-leaning rake, resulting in more blade area for a given diameter, does not interchange directly with a Fed prop pitch-wise)

I was pleasantly surprised to here what Mr Weeks told Waterdog. While a 540 on many boats really picks up perf, it definitely slowed my light 16 boat turning in the 5000+ range. Waterdog, you most likely have a 12x14 and for a 350 ci it may be a little short on pitch. I will be glad to lend you a 12x15 or 12x16 when you get to the test point. With the mods mentioned, 5500 seems a little high to me also, but it might do it with a 12x14, albeit not with the best perf. If you haven't installed the cam yet and not knowing what your perf goals are, a .410" lift cam is very stock, but not knowing the duration it's hard to say. The good cams being run in most of the Fords on our site here are in the .450-.500" range in terms of lift and 206-225+/- degrees of duration. These by the way are in the neighborhood of and slightly better/higher than what was used in a stock 5.0 HO Mustang car, which wasn't a slouch but didn't behave eractically or have any idle issues. FWIW.

Reid -
Thanks for the offer on the prop,I'll take you up on it. I need to get the foam & floor complete. I'm off on monday & plan an all day thrash on it. The engine is a 355 cu.in. chevy .410 cam is 202/213 @ .050 lift - But with 1.5 rockers, I've got 1.6 full rollers with 100 lbs. springs in it . We did the math a couple months ago so my memory is a little fuzzy , I think it ends up .437 valve lift ish ? Performance Marine built it expecting 300 h.p.@ 4800-5200 rpm. 198 hp stock 300 hp now - it should get out of it's own way. Can't wait to get wet in Lake Gaston !    

TRBenj
I'm not an expert on Ford vs Chevy Chevys do like to spin a few hundred rpm,s faster & fords like to pull like a tractor with low end torque. Does the Ford timing chain vs Chevy gear drive have an effect on it ? Do you think 300 hp is in the ballpark. The engine parts are "geared" more for endurance than drag racing.     

Waterdog wrote: Does the Ford timing chain vs Chevy gear drive have an effect on it ? Do you think 300 hp is in the ballpark.

I couldnt tell you- my limited knowledge really only applies to the Fords. I would think those mods on a 350 would get you to 300hp though. With intake/heads/cam/DUI on my 351w, I figure I gained ~80, which would put me at 320hp.

boat dr wrote: Knowledge Is Power...........

Speaking of.... ever find out what Fromunda Cheese is???

reidp
   Intake = Edelbrock Performer (port matched)
   Holly 600, 198hp vs 300hp 1600# + 50% power gain = Whooo Who !!!

Fromunda Cheese?? Hmmm?   Bet it goes good served up with a Cleveland Steamer.

I'll use that as a segue(I like that word)to: Has anyone ever seen one of the Cleveland head 351's that Commander marketed back in the mid-late 80's. They called it a Clevor as it used the Cleveland style heads on a Windsor block. I only saw ads on it. They said it made 520 HP and would push a CC 82 mph. Just kidding, believe the HP was only 260. I've never been aware of any other 351-C marine engine applications/conversions from an OEM.   

Actually a 305 and 350 GM should weigh almost exactly the same. Unlike the 302-351 Ford comp, the GMs are almost completely interchangable with all external dim's being the same. This goes from a 265ci all the way to a 400 small block, right Bowtie boys? If a Tique with 190-230 HP runs 45-50, then 300HP ought to put you mid 50's. I guess I need to go back to my parts bin as I'm feeling an inadequacy attack coming on.

Chuck, As of now we no longer have a Nautique running with a 318, but the two we did both turned a 13x13 prop at 42-4400 rpm, and ran 45 and 47 mph by the speedos. I made up all that cam stuff and no one's even called me on it yet.