Stringer Design and Floor Replacement Questions

[atengnr]

Hello all, have this 68 saftmate that has been in family since new. Long story shortened, in 2009, I had a local shop replace center stringer, and floor (I had done side stringers and floor in 1990s). Shop did a substandard job, as they did not tab the stringer, only used a resin chopped glass paste to bed stringer down. Also they did not glass the floor on top. Finally getting around to fixing this, but also noticed that an old crack repair that shop did has cracked again (this was from damage done from a chisel into hull during my work on it in 1990s). So, what is my best course of action? Stringer is solid, but open to environment. Should I remove all of floor to glass stringer in correctly? How should I fix the crack (inside or outside?). Any thoughts on modifying stringer design to make this boat more solid (I do like to take this boat out on great lakes occasionally, and it gets beat up, albeit at 10mph)???

Thanks alot.

 

[chevymaher]

Yes pull the floor and tab and seal the stringer. Do the bottom of the floor. Put it in and do the top. And what about the flotation foam your not talking about.

 

[atengnr]

Thanks. Could i stiffen this boat up by adding some bulkheads? Yes, should i put foam in? How about fixing crack? Best inside or out? Thanks.

1708 biaxial is the best tabbing material these days? Back in the90s i tabbed with woven roving after a layer of csm. Also just use csm on top of floor?

Thanks alot

 

[chevymaher]

Yes 1708 is the stuff. Same as your used to using. Just the CSM is sewn to the roven for ease of use. Add bulkheads stronger is better. Foam makes it quieter and stronger. Plus you live if it dont sink. There a formula for figuring how much you should use. Any place you can put it is my rule of thumb.

There are several stringer bulkhead configurations these boats use pick one you like and go with it. I have seen 3 boats like mine. same tpye and year boat. They had different set up similar but different. Depended on who was doing it that day is my guess.

I used 1708 on top of the floor but yes CSM is sufficient.

The crack depending on how bad it is. Not so bad put 3 layers inside each one 6 inches bigger then the last of the 1708. If it is bad both sides is the preferred and strongest method. Boatworks has a nice tutorial on fixing a hole in the hull. same thing it goes through the crack. If you go that way I can find the link.

 

[atengnr]

Thanks alot. How far apart should i place the bulkheads?

What foam is best to use?

this crack is about one inch long.

Thanks

 

[chevymaher]

Where is the crack and a pic. Is it in a structural area or in the cap.

Most boats have 2 bulkheads. One ahead of and behind the gas tank. Foam is 2 lb 2 part foam. You get it at US Composits in florida.

 

[atengnr]

Crack is in hull

 

[atengnr]

Crack is in hull

 

[atengnr]

Crack is in the hull.

this boat has no integral fuel tank. Should i set up one every 3 feet or so ?

 

[atengnr]

So pulling this floor apart and fhe workmanship was quite suspect. This joint had filler on top of floor only and joint easily pulled apart. Also see how stringer was tabbed in only with fiber thickened resin.

 

[chevymaher]

Okay here is my patch of a staple hole. gel coat was barely cracked outside. I tapered it inside and out but only glassed inside. Outside I used gel coat.

Next picture is the keel. 6 inches of csm on both sides and over the top with 2 layers of 1708. And the last layer is as wide as it is wet.

Here is the spacing on my bulkheads one ahead of the engine compartment. And one where the ski locker is.

Here is a link to a set of 3 videos teaching how to repair holes. Watch it and make your call.

https://www.youtube.com/watch?v=i9hfpOCnzEs