16ft Larson I/O trihull help

[eclipseturbors]

Long story short, sold sold a Mark Twain that needed alot more work than I was willing to give and bought this 1970's 16ft Larson Trihull with a 120 Merc I/O. It came on a tandem axle trailer that was worth the $300 I gave for the whole bit. So I started stripping the "Hugger" orange paint off it to paint it. While stripping the inside, I found a soft spot I missed while jumping around in the boat. Now I'm in it for a floor, maybe a stringer (haven't got that far yet), and a transom that had a new board attached to the rotton original. The last guy must have replaced the floor at one time.. It's pretty funny... I'll try to get some pics of the realtor signs screwed in there under the rotting floor. My question is that the foam under the floor in the rear looks like low density foam and doesn't appear structural. It's like 1/2" or less thick. Should I even bother with it? I can try to shape the pink HD foam in there I guess. Also, the further forward I go, the better it looks. I really don't want to tear out another 10ft of good boat. I have 2 beams that are wood and looks to run the majority of the boat as some sort of main stringers... Is it possible to sister the beams to new good wood? Lastly, I am gun shy about pulling the motor because I have never re-installed in I/O. Anybody have a link to the best way to installing a 4 cyl Mercruiser? I will get some pics today. Oh, yeah and I have a tight budget... that's like a joke when repairing anything old, especially boats.

 

[Cadwelder]

Re: 16ft Larson I/O trihull help

You said you sold the Mark Twain because it needed a lot of work? How much more did it need compared to a stinger, deck and transom job on this one?

I'll wait for the pictures on the rest of the advice needed.

 

[eclipseturbors]

Re: 16ft Larson I/O trihull help

The Mark Twain needed all the gel coat stripped off it due to the massive amount of crazing on top of the whole boat needing gutted. I got called to work, so now it won't be until much later before I get the pics up. I think a trihull is going to fit my family better anyway. I think that I will make it more into a fish and ski type of boat.

 

[eclipseturbors]

Re: 16ft Larson I/O trihull help

Here are 2 pics taken with my terrible phone cam of the carnage so far. The transom is completely shot, so I guess I will be pulling the drive off in the morning before work and prepping to pull the motor sometime later this week. Any suggestions on how to attack the stringers? Will they be foam and how do I repair if needed. Also take note of the realtor sign... just makes me laugh a little.

 

[eclipseturbors]

Re: 16ft Larson I/O trihull help

After reading a few posts of transom replacements for I/O, I am a little confused of the overall needed thickness of the transom... I have the drive out and the engine is ready to come out of the boat as soon as I can get my hands on an engine hoist. Can I also replace the transom with the gimbal and carrier assembly still attached on the outside of the boat? I've never removed one, but I am willing to try none the less. I have never owned a trihull and still do not know what to expect as far as stringers. The wood that runs parallel to the motor is definately rotted out. It doesn't appear to be very thick though and has foam underneath it? If someone could link me to another resto on something similiar to what I might have, that would be greatly appreciated.

 

[eclipseturbors]

Re: 16ft Larson I/O trihull help... more pics and questions

Re: 16ft Larson I/O trihull help... more pics and questions

Well, I've got the motor almost pull all the way out of the boat. This only exposed more rot. The wood stringers are about 11" wide and 3/4" thick pine I'm guessing. There is non-structural foam under the wood. Can I use the pink hardware store foam under this wood? I believe that the stringers run to the front of the boat or at least most of the way. There was no floatation in the middle of the boat but plenty of real estate signs. I just want to be sure that the only thing holding this boat together is some floatation foam and 2 pine boards? Please chime in if you can help.