Larson Trihull Restoration

[martymcfly]

Just traded my 14' Lund with a 1955 Evinrude 15 fast twin for an 80's Larson 16' Trihull with a 70's Evirude 85. I knew prior to trading that the floor was shot, but didn't realize how bad. got it home and started to gut it. Rot everywhere, no good wood, completely saturated foam. Pulled around 500 lbs. of wet foam out of the stringers, as this hull uses foam under wood for a stringer. Plan is to replace transom, replace all the stringer wood, fiberglass it all in, add a ski locker. Entire interior will be reupholstered with marine grade vinyl. Should be a good project, I hope to get it done for spring.

As purchased pictures








I love how it was sitting on a hill, bow down, just full of water, no cover. People just don't care, or know for that matter.



Stripped out the plywood floor what was just sitting on top of the foam. Someone obviously rigged a quick floor.

 

[martymcfly]

Re: Larson Trihull Restoration

continued...



Time to started removing the bad.





Couple of quick questions.

I am not going to be splitting the hull and removing the top, however, I'm not against cutting the rear splash area out in order to redo the transom. Can someone give me some info, or point me to a thread where someone cut out the rear splash well area.

What type of wood should I use to replace the lumber frame work?

 

[jigngrub]

Re: Larson Trihull Restoration

Looks like a Party!!!

Most people use exterior grade ABX, ACX, or BCX plywood, it's cheaper than marine grade and made with the same glue. Don't use pressure treated or interior grade plywood.

You'll also need a butt load of polyester resin and 1708 biax cloth... and other stuff too.

Take time to read some of the other restoration threads here before starting your project and it'll make life a lot easier for you.

 

[martymcfly]

Re: Larson Trihull Restoration

Looks like a Party!!!

Most people use exterior grade ABX, ACX, or BCX plywood, it's cheaper than marine grade and made with the same glue. Don't use pressure treated or interior grade plywood.

You'll also need a butt load of polyester resin and 1708 biax cloth... and other stuff too.

Take time to read some of the other restoration threads here before starting your project and it'll make life a lot easier for you.

Ive been lurking on the site for some time, lots of great info here. Been reading all the floor and trihull threads.

 

[GT1000000]

Re: Larson Trihull Restoration

Hi and welcome, martymcfly...
Nice looking project you got yourself...heard those tri-hulls are real nice and stable rides...gonna be nice when done.
Yeah there are several guys that have just cut the cap back at the splashwell and replaced the transom...
I don't have any links right off, but I'll look and get back to you...or someone else will jump in and point you in a the right direction...
As far as types of wood...
Most boats are built using one of several different types of plywood...
ACX, BCX, MDO, Marine Grade, Underlayment, Arauco...the biggest quality to look for is that the plywood be laminated using waterproof glues...
Kiln dried Pressure Treated is also a good choice, but it has to be almost bone dry for the resins to stick to it...
There is another type of plywood being used by boat manufacturers now...
Product Information
Welcome
Best of luck and have fun!
GT1M

 

[bakerjw]

Re: Larson Trihull Restoration

Welcome. Personally, I'm one of those that's for decapitating boats. It looks like you're well on your way with the demo work which is the part that really sucks. Oh to do a restoration of a boat with only 2 stringers and no bulkheads! I had 4 larger stringer, 22 small bulkheads and 3 large bulkheads. Now that will eat some fiberglass and epoxy. Yours will be material cheap. Good looking rig.

 

[martymcfly]

Re: Larson Trihull Restoration

I was referring to the wood that makes the stringers and cross braces. They aprearred to be almost like a 2x8 layed flat for the stringers and 1x3 layed flat across the stringers for the cross braces. Can I just use any lumber to remake this framework?

 

[GT1000000]

Re: Larson Trihull Restoration

Not just any wood is good for boat building...
Douglas Fir, White Oak, Mahogany, and I think Cyprus and Southern Yellow Pine... there are others, but those are the one's that come immediately to mind...
You can also get some ideas of good species of woods to use from a site like "Glen-L"...Build Your Own Boat

 

[jigngrub]

Re: Larson Trihull Restoration

Don't use pressure treated wood, it has a high moisture content because of the pressure treating solution and your resin won't penetrate or bond properly.