Stringer Replacement 86 Silver Nautique. |
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Posted: October-21-2022 at 4:12pm |
Finally pulled the trigger on replacing the stringers on our Silver Nautique, been on the list for a decade. I will post pictures over the winter, with the ambitious schedule to be done by late spring for skiing. Over the weekend I pulled the seats and vinyl, dropped the rudder, pulled the shaft, removed the gas tank and other misc. stuff. Had our boat mechanic pull the engine and store it. Best $200 I’ve spent in a long time. He thinks the motor is in good shape but will do a general review and a cylinder compression check while he has it. My plan is to hang the boat to pick up most of the weight. I’m also going to put supports under the two back corners and one support centered up front, just before the flat spot ends under the boat (just a bit in front of the fins) to keep things still while we work. Those supports will also help me level the boat for the glass work. I’ve been reviewing stringer materials and, of course, recommendations are all over the place. I don’t think the bottom of the boat is really designed to flex, fiberglass is pretty rigid in plane and flexing the string encasements would crack them. So I’m not worried about picking something flexible for the stringers. My second choice is white oak: strong, stiff, highly rot resistant and not very expensive. But oak is not dimensionally stable, it will expand and shrink a bit depending on moisture. Yep, theoretically no moisture should get in there but, well, stuff happens… Same stability issue exists with most other solid wood choices (Douglas fir, etc.) My current first choice is Marine Ply, laminated together to get the right thickness, with staggered joints. Will be stiff, soaks up penetrating epoxy well (unlike oak) to make it more rot resistant and is dimensionally stable moisture wise. Forum thoughts on this are welcome. |
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Hung the boat from the lifting rings today. Braced in the back corners and either side of the center just in front of the fins and drove some thin shims between the hull and the supports to take a touch of load off of the lifting rings. Easy enough to level it side to side. Front to back was harder since nothing seems to match. Decided to make the floor level, which put the existing aluminum engine support slightly out of level front to back compared to the floor but I doubt that matters much. |
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Deconstruction currently held up by the pylon. I searched but couldn’t find any specific directions to remove the pylon beyond pulling the stainless bolt that goes through the bronze fitting at the hull and knocking out the lower pin that goes through the base of the pylon and tapping the pylon up with a hammer on a wooden block through the ring. Not working, even though the pylon moves just at touch on the steel pin that connects the pylon to the bronze fitting. Picture below. Love to talk to the dude who though it a good idea to tie a bronze fitting to an aluminum post with a steel rod. My next move is to put a post on either side of the boat, run a beam over them and put significant upward tension on the ring with a come along, heat the base of the pylon and tap up on the ring with a block of wood and a mall. Any other ideas are welcome. After tapping up on the pylon I noticed a touch of moisture around the base of the bronze fitting at the fiberglass hull which I don’t think was there before. So I’m likely going to need to grind down around the fitting, see what’s going on and fiberglass things back together. Anyone know exactly how the bronze fitting is set into the hull? Picture below, but tough to see the moisture. |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Soak it with a 50/50 mix of acetone & tranny fluid. Let it soak for a couple days reapplying and tapping with a hammer daily.
Then heat the brass socket to draw the fluid in… squirt, tap, heat and repeat. Good luck 👍
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Well that was a total fail. I put enough upward pressure on the pylon to lift the boat slightly off the chocks in the front, put some ice around the bronze fitting to keep the fiberglass cool and heated the base of the pylon to 250 degrees. Used a piece of wood and a mall to hit upward on the ring and got nothing. So looks like the pylon stays in during the repair. I will, hopefully, be able to remove the ring later today so I can slide the aluminum motor cradle off the pylon and get it out of the boat.
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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Need to twist it to break it free. Get it good and lubed up first, and get a couple heat cycles on it. Small pry bar through the ring and finger (protected by a rag) should do it.
Can’t imagine doing a stringer job without it out of the way. |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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What Tim said but just be very careful when twisting from the ring finger, it will bend if you apply to much pressure. You may be better off getting a big pipe wrench and twisting from the bottom.
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Removed most of the fiberglass flooring plus all the foam under the front deck over the weekend. I don't think i'm going to reinstall the hump under the front deck, just going to run the flooring through flat. i've got some mahogany laying around from an old bleacher tear out we did, I can make a foot rest from that and attach it to the floor. Don't see any real need for that hump full of foam. Boat has been out of the water and under cover for 2 months but bottom 2" of foam was still soaked.
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Now you should be able to get a big pipe wrench on the bottom of the pylon.
Since I already did a complete gut and stringer job on my ‘85 I would suggest only tearing one side out at a time. It’s a whole lot easier getting your heights and measurements when you can mirror the other original side. JMHO
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Used a diamond blade on a grinder to cut the rest of the flooring back right next to the sides, worked pretty well. Holding a vacuum in front of the blade kept any dust to a minimum. Then removed all of the foam. Just for fun I weighed the bags of old wet foam, came up to 155 lbs, which is less than I expected.
Next steps are to use a sander to remove most of the old carpet glue on the sides of the boat. Then mark a line 12" above the current floor location so I can locate the floor after I grind the last of the floor fiberglass off of the sides. After that I will make a drawing of the secondary and primary stringers so I don't lose any information. Then (following gun-driver's suggestion) cut out and rebuild one side of stringers. I was planing to use marine ply for the stringers but finally looked up Coosa Board after seeing referenced often and realized that it's not wood but a stiff composite, so planning to head in that direction instead. Also spending time thinking about a deck material, anyone familiar with Nidaplast-8? Seems like 3/8" or 1/2" would make an excellent base material for the deck. |
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Wilhelm Hertzog
Senior Member Joined: June-14-2014 Location: Cape Town Status: Offline Points: 334 |
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My boat's floor is made from Nidacore/Nidaplast. Only drawback in my experience is that it doesn't hold screws very well. I've had to create some epoxy plugs in the floor to give screws that experience high loads something to better bite into.
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1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer
Do not go gentle into that good night. Rage, rage against the dying of the light. |
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Excellent! I need to find a local source for Coosa and the Nidaplast. There's only a couple of floor fastener locations, I may just glue some treated 2x under the Nidaplast at those locations.
Sanded the old glue off the sides with a palm sander and 80 grit paper today. That went pretty easy, though I didn’t try and remove every bit of old glue since the fiberglass was pretty rough and removing all the glue would have removed a significant amount of glass. to locate the new floor, I drew a line 8” above the old floor onto the sides of the boat, then checked that with a level front to back and from side to side. It was close but a bit out in every direction, especially under the bow. Basically, the old floor wasn’t really flat or level in either direction. Since that’s how I originally leveled the boat, I decided to back up and check the stringers against the top of the boat sides. They were close but didn’t actually match level wise, not really surprised at this point. Since I can’t tell which are actually true to the bottom of the boat and they were close, I used the tops of the boat sides to re-leveled the boat side to side. Secondary stringers ended up about a ¼” out of level to each other with sides perfectly level, easily close enough for this project. Still needed a way to level the new floor so I pulled a string line down the center of the boat, bow to stern, and set it roughly 8” above where the old floor was. Then I leveled the string front to back. Laying a straight edge side to side across the secondary stringers and measuring up to the string, I had 8” at every stringer point I checked. I leveled from the string to the sides of the boat and put marks about every foot, used a short flexible straight edge to draw a line between marks from the stern all the way to the front hanger point under the bow. End result is a level reference line on the sides of the boat to locate the floor and the tops of all the stringers. Next up is grinding the remains of the old floor off the sides of the boat, planning to use a coarse flapper wheel and that’s likely to be ugly dust wise. Need a vacuum shroud for the grinder or a wide pickup for the vacuum. |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Don't waste your time with flappers get these.
I buy mine at a local autobody supply. (I try never to buy from Amazon)JMHO
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Away for the weekend, looking over pictures and making plans. Realized that I didn't take three dimensions before I started the tear out. Can anyone with a Sliver Nautique send me the following dimensions?
pylon to base of observer's seat. pylon to inside edge of battery box. pylon to base of driver's seat. Thanks Andrew
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Sides of the boat are mostly prepped for glass to attach the floor. This weekend I removed almost all of the stringers, still have the bottom inch or so of the main stringers to get out and a lot of grinding and sanding to do on the bottom of the hull. The secondary stringer came out pretty much intact with just some rot in the tops so I can use them as templates. The main stringers are attached hard to the bottom of the boat. Probably going to need to splinter the rest out with a hammer and chisel. Tops of the main stringers were trashed with rot. I was able to create a detailed layout of the old stringers on paper so I went ahead and removed both sides. I cut one side of the stringer fiberglass about 1” above the bottom of the boat to leave a lip and cut the other side flush with the bottom. I will use the lip to locate the new stringers and I’m planning to use one of the 3M adhesive caulks to attach the stringer to the bottom of the boat and hold it still while I wrap them in glass. Figuring the depth of the cuts in the stringer for the layout went a lot easier when it occurred to me to use one of the small laser levels we use on jobsites. Set it on the 8” line I’ve already established, which was pretty accurate with the laser level, and then measured down to the stringer at each elevation change. Also pulled the windshield. I need to repair the blocking under the deck so the screws will take up, find a gasket to put between the deck and the windshield so we stop taking water when one of the kids buries the bow in the wake looping to pick someone up. And find someone to powder coat the metal. |
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Looks like some people put the foam back in and some leave it out. I lean towards leaving it out, less work and less weight. Anyone want to weigh in on the pros and cons? Other than the boat will sink if it fills with water.
Don't think it would float anyway, there's not enough foam to offset weight of the engine, the hull and the other steel, aluminum, bronze items plus beer and sand. Boat weight 2300 lbs / 62 lbs per cubic foot for water = 38 cf of foam, pretty sure I didn't remove that much foam.
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11090 |
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No foam .....it's like a submarine sitting on the bottom
With foam....it's still like a submarine but it's at periscope depth hovering up near the surface where you can still see it Otherwise I don't have an opinion for you PS your boat weighs a lot less when it's underwater so your foam requirement would be different
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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A little far along to be just starting to thing about rebuild strategies!
If you eliminate foam (which I would also recommend), you should consider replacing the strength of the foam with additional structural members. It also affects your options for flooring, floor height, etc. Obviously it’ll affect material lists as well. |
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3363 |
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Indeed, that math didn't factor displacement
early ski supreme before they went to composite in 86 had 4"x4"x8' foam strips in the lower hull, fastened to the hull with little straps of glass. not cavity-filled, so they see some air and have a chance to dry out. . Hence some pool noodle solution some have used.
There is also more foam higher up, inside each inner gunnel that wraps to the floor. these stay very dry over the decades.. and the bow is filled with foam. This all together met level flotation requirements at the time and makes the boat recoverable, without accumulating much water weight/ bloating over the years. Consider some of those techniques if your want the boat to be at least recoverable if things go awry and wont have to search yellow pages for scuba |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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All good points. Hadn't considered the decrease in weight as the boat sinks.
I would say that short of a catastrophic event I can't imagine the boat sinking, but there was that one time years ago when we forgot the plug. Somehow my youngest son heard the sound of water over the engine noise as he pulled away from the ramp and opened the engine cover to see a fountain... Now his first question is always "Dad, did you put in the plug?", not sure why that's my job!
I was wondering if there was a structural component to the foam but that seems like a bad way to design a boat hull. I can easily add a couple of stiffeners running perpendicular to the stringers. Probably just from the secondaries to the sides of the boat, which is were most of the foam was anyway. The bow was full of foam but the curvature of the fiberglas hull in that area adds strength above just the thickness of the fiberglass. I will leave the floor elevation where it was, don't see any need to change. Noodles?! that's an odd and interesting idea. Lightweight closed cell foam, loose so water can drain around them. Easy enough to calculate the cubic footage that will fit in the available spaces. I will play around with the volume of the various solid parts of the boat and try to come up with a displacement number and see if noodles could float the boat at periscope depth. Anyone ever see or hear of a sunken ski nautique? |
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Riley
Grand Poobah Joined: January-19-2004 Location: Portland, ME Status: Offline Points: 7953 |
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What happened to the pool noodles for flotation in the early days of CCF? How did those boats work out? There were a few people that tried it.
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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They sank Bruce taking their captains with them.
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11090 |
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While you're noodling over what you're gonna do, here's a link to some CCF threads about using pool noodles for flotation Like everything else you'll get differing opinions and all noodles aren't created equal either I'd figure.
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Tomrupp
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I like the star shaped large noodles from Wally World. Don’t do the wrapped model because they get waterlogged. You might end up listing and get swamped by a wake boat swell.
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Tom
94 Ski Nautique Open Bow 351 with Carb 95 Double Decker Aqua Patio with 50hp Honda (3 carbs). |
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Ok, no noodles. After reading lots of posts, foam is back in the project. Sound dampening was a large driver in my decision. Since I'm planning to use a composite board for the floor I don't need the foam for any significant support so 2 lbs foam should be fine and gives minimal weight gain.
Various posts discussed concerns about trapping water somewhere under/around the foam which I was worried about as well. In construction we use a plastic drainage board to eliminate hydraulic pressure against below grade walls, should work here to allow water to drain from under the foam. See the picture below, install dimple side down, pour the foam on top, put drain holes through the base of the stringers into the bilge. Still thinking this through, the drainage board could just move the trapped water up between the foam and drainage board. Also seems like there is just no place for water to be trapped in a fully foamed compartment... |
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uk1979
Platinum Member Joined: June-13-2007 Location: United Kingdom Status: Offline Points: 1423 |
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I have played around with foam in the hull... if you go with
foam (closed cell type) try to keep the hard skin which forms on the outside of
the foam as its less likely to soak up moisture. I went with lining the area with DPC (Damp Proof Course Polythene) leaving plenty
running over the sides to fold over the top to seal up once set. After setting and sealing you can the lift the foam-covered
blocks and any puckering of the DPC can be shrunk using a hot air gun, I went
with a second covering of DPC and shrunk it over the first with the hot air gun
and the blocks still fit back in the hull, that up to you. The older hulls do let water through only by a very small
amount, but over time/years it’s a problem, once you have finished the stringer
work clean back the hull of all old coatings and tank it all in epoxy resin 2 coats the second before the
first is fully dry. Moisture will always be in the hull just by temp changes its
just keeping as low as you can. Thanks for saving an old SN and keep the pictures coming good
luck. roger. |
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Lets have a go
56 Starflite 77 SN 78 SN 80 BFN |
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samudj01
Gold Member Joined: March-10-2009 Location: NC Status: Offline Points: 974 |
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Enjoying this thread. Keep up the good work! Think about using thickened epoxy to bed the stringers instead of 3M caulk.
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78 Ski Tique, 72 Skier w/302's, 93 SN w/351 & 17 GS22 w/zr409
Previous - 99 Sport Nautique w/GT40 and 87 Martinique w/351 |
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blammie
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You posts are well timed for me. I'm hoping you'll post more pictures. I'm just starting on my '68 Barracuda. I'll be interested to see your progress as you lay stringers back in. This is the part of the job that has me most worried.
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andrewmarani
Senior Member Joined: May-31-2005 Location: Baltimore, MD Status: Offline Points: 249 |
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Got the last bit of main stringers out with a router and a half inch bit, used a guide to keep the bit in the middle of the stringer and cut down ALMOST to the hull (was very careful about that!). Then I was able to split one size of the stringer off in small pieces and pop the other side out in large lengths, so not as difficult or time consuming as I expected.
Pulled the windshield and knocked it down into it's component parts, will be sending the aluminum out to a local powder coat company for a new black finish. Trying to decide between a satin, semi or gloss sheen, any thoughts? I'm now into the apparently never ending grinding stage to prep the hull for fiberglass. I will post a picture once it looks like something has actually changed. Got pricing on Coosa board from a local supplier for the stringers. After laying things out, I will need 2 sheets of 1/4" for the secondaries and 2 sheets of 1/2" for the primaries in order to laminate up (3 layers wide) to get the lengths and widths I need. OMG that stuff is expensive. Still planning to go that way, just had to take a deep breath and adjust to the cost before I actually order it after getting the quote. The honeycomb board for the flooring is not available locally but some research on line says that the 26 lb Coosa board would work well for the floor but the 20 lb is too flexible. I will be going over 2 lb foam and am now planning to use 1/2" 26 lb Coosa. Anyone have a thickness recommendation? Only want to buy this stuff once! |
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3363 |
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For the floor you could consider using the lighter density 3/4 coosa as a core and just epoxy some mat to both sides. it gets very rigid once the glass is there on the outside to take the brunt of the compressive and tensile forces.
and still wouldn't foam-fill it. neither my supreme nor response are foam filled, and they are the quietest boats in the local fleet of my hommes
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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