Stringer Repair 1985 2001 Ski Nautique

Forgot to mention the bilgecoat...

I wanted to use gel as I also think it's the best skin for the bilge, but I didn't for lack of time and equipment. I used white BC without the flakes(if I remember right) and it's held up very well; much better than I expected. It's very durable and easy to clean.

Does the boat have the same attitude now as it will have in the water? Will it float like it is sitting?

TRBenj wrote: I thought I was clear, but somehow I am failing to make my point... From the transom of the boat to the front of the engine compartment, the mains are fully exposed- even when the boat is finished. The floor does NOT attach to them. They are exposed in the engine compartment, and a removable panel sits on top of them just aft of that. The gas tank sits on them all the way in back. Nothing "glues" on top of them, floor or otherwise. This is why they need to be wrapped over the top in these areas- to make them fully sealed, added impact resistance, etc. Agreed, this is not rocket science.

+1

Isn't an '87 hull built with polyester? So the Bondo should stick to original hull laminate?

Trying to get the bilge to drain perfectly will be an exercise in futility. Filling low spots as deep as 1" with low strength filler is impractical and ill advised. Poly based fillers like bondo won't stick well to epoxy either. I'd leave it be.

I've tried several bilge finishes and like gelcoat best.   With a vinylester conversion coat over the epoxy, gel can be brushed on. It'll lay down pretty well and look good with 1-2 coats. It'll also be very durable. Bilgekote will NOT stick directly to epoxy, it needs a special conversion/primer (ask me how I found that out). It's decent stuff as far as paint goes but gel is no more work, more durable and similarly priced.

TX Foilhead wrote: I'm suggesting the same thing you drew last May with some additional layers of cloth over the top. If it is all laid down at the same time then is cures as if it is a single piece and should be strong enough to do the job. All you're trying to do is glue a board to the floor and keep it from getting wet and rotting, we're not building the space shuttle here.

I thought I was clear, but somehow I am failing to make my point... From the transom of the boat to the front of the engine compartment, the mains are fully exposed- even when the boat is finished. The floor does NOT attach to them. They are exposed in the engine compartment, and a removable panel sits on top of them just aft of that. The gas tank sits on them all the way in back. Nothing "glues" on top of them, floor or otherwise. This is why they need to be wrapped over the top in these areas- to make them fully sealed, added impact resistance, etc.

Not sure if youre thinking of the secondary stringers and how they tie to the floor, or if youre just way out in left field. Take a look at the pic I posted above, it should be pretty clear?

Agreed, this is not rocket science.

If you use the same cloth & resin in a composite lay up ,fiberglass,Kevlar(nomex),carbon whatever
The strongest part is determined by cure type, autoclave is far and away best. Second best is atmospheric pressure (vacuum bagging/ resin infusion , then wet lay-up.
With an autoclave you still use vacuum pressure at first and bleed off the vacuum as the external pressure is applied. External pressure can be as much as 100 PSI.
Bagged parts are very good quality with minimal porosity
The hang up is the time it takes to lay up the part with the bleeder schedule and bagging it.
Room temp resins will kick if you have a medium or large part.
So pre pregs are used (resin infused fiber) frozen rolls that are thawed the night before and cured in an oven. Usually temps are 250/350*f
When using a wet lay-up weigh out small amounts of resin never more than 400 gms. On a large lay-up
weigh out several cups then mix them as needed to avoid an exothermic reaction.    

Infusion can burn up a lot of money real quick and leave a huge mess thats hard to clean up, but if it worked it sure would be easy and it would leave you with a stronger end result. My thinking is that you would have to be familiar with the process from doing smaller parts first so you could work out the specifics of doing something as long as a stringer. I would guess a stringer would require some sort of manifold on each side to pull resin from the floor level to either the top or across to the other side from more than one spot. The benefit would be that you could use less resin and possibly less cloth and end up with as strong a laminate as possible.

If they can do whole boats with it then a stringer should be no problem, we just don't have the advantage of using a highly paid consultant or engineer to work out all the bugs for us in advance. It's definitely on the list of things I would like to learn to do, just don't have a reason to move it to the top right now.

I didn't say don't wrap them, I said you don't need to have a complete piece of biax across the top. Use biax like tape on the floor and the sides and tie the layers together with cloth that covers everything. Not as strong as one piece would be. The only difference would be a little less strength in the direction the stringer is least likely to break, there's still fiberglass over the top.

Bagging a whole stringer would be quite a chore for someone who doesn't have a lot of experience with the process. I think you would have an easier time with resin infusion, but its still something that you should work the kinks out of the process before you attempt a whole stringer.

If you have to start over, run a round over bit down the top of the stringers to make it easier. Since everything will act as one structure when its done, some biax on the floor and up each side of the stringer covered with some woven cloth to tie it all together would be easier. I doubt you need the strength of the biax going across the top of the stringer with the floor sitting above that.

I have looked at quite a few race boats where they used very little material to keep the weight down, but the boats still take way more abuse then our boats will see. I think we seriously over do it with materials to make up for the fact that we don't know exactly how much we need and if its being done correctly. I'm sure it will be fine, I've never seen someone post about blowing their new stringers out. There is an interesting thread on Wakeword where this will likely happen, but he glued new wood to rotten stringers and then covered it with bed liner.

TRBenj wrote: I think you'll find that mat is about 90% as difficult as the biax when it comes to curves. Try letting it tack up a little before molding it over the stringer.

I'm assuming you missed this note from before. The mat will not be appreciably easier to mold over the tops than biax. Both are thick, and thick stuff doesn't do sharp corners well- let alone 2 90's over an inch or 2 span.

Put it in place, wet it out, then form over the top. It will come off, as you've noticed, but the next part is key- wait a few minutes (allowing it to tack up slightly) and try again. Repeat as necessary.

Btw, if the secondary stringers will be capped by the floor and won't be exposed to the bilge (as is common), no need to wrap the tops of those. Most people don't.

I dont recall what the failure was, but if you are worried about layup nothing beats vacumm bagging for a pristine layup with minimal epoxy.

captbob626 wrote: Great Post, Just began cutting the floor today on my 83 ski nautique, Was hoping the stringers were OK but were pretty wet under the observer seat. Guess I'll have to replace stringers. How far forward does the main stringers go? I cut up to about 1" behind the air box and haven't removed any foam yet. cannot see the forward end with all the foam.

Best thing you can do is to start your own thread, and post pictures as you go. Lots of very capable hands here to guide you (me not one of them).

lol

Good luck.

I agree you've done most of the hard work already..
And it could be worse ive owned mine through 2 seasons and am still yet to get it wet!!!!!!

iplan wrote: I think I'm going to get the stringers in, and take all my materials up to the local boat yard, and pay them to get it done ~ and done right.

Dont concede yet! Youre heading into winter- you can get this done before next summer. Stick with it.

While Im certain the local boat yard would be happy to take your money and give you back a working boat, I would be very skeptical of them "doing it right". I have not yet seen anyone pay for a stringer repair job that was done to the standards set by the worst stringer repair documented on this website. I have no doubt youre more capable of finishing the boat properly than someone who is paid to do it.

I think you'll find that mat is about 90% as difficult as the biax when it comes to curves. Try letting it tack up a little before molding it over the stringer.