15' tri-hull fishing boat rebuild, questions/updates

[Hydrilla]

I've posted a couple of times here, and have a couple scattered threads that have scrolled off the recent pages, so if y'all don't mind I wanted to just start a central thread I could use for this boat project. I do search the archives a lot, yet I know I'll continue to have specific questions since I've never done this before. I appreciate all the help so far.

OK tonight me and my son cut into the deck some more with the sawz-all. I couldn't be more glad that we decided to scrap the whole deck. Much of the floor was still ok, but the foam is completely SOAKED from bow to stern. Also a section of one of the stringers is bad, probably about an 18" section that we've found so far. From what I've read, you can replace part of a bad stringer/stringers, is this correct? Everywhere else that I hit so far, seems really solid. Do you recommend for/against this?

One more question for now. I'm building this into a bass boat with raised front and rear decks, much higher than the current ones. Since the stringers don't go up that high obviously, am I going to have to build a subfloor where the current deck is, and then raised decks on top?

Here is a close-up pic of a section of the foam and stringers. If the pic doesn't show up correctly, you can see it at the end of my share-a-project page. Thanks muchly for the help guys.

 

[tashasdaddy]

Re: 15' tri-hull fishing boat rebuild, questions/updates

you can patch the stringer, buy replacing the bad section, the sistering a piece of each side of it. with a 2 ft lap on each end, and both sides

glue and screw it all together.

 

[tmcalavy]

Re: 15' tri-hull fishing boat rebuild, questions/updates

Be careful raising the floor, you also raise the center of gravity in doing so and that can affect how stable it is in the water. I'd consider putting the deck back in as it was and then installing removable fishing decks that you can put in/take out at will...based on whether you are going fishing or just crusing on the lake.

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

Tashasdaddy, thanks for the pic and description of the sister joint. And thanks for resizing my too-large pic :redface: I think there are only a few bad areas, so this will probably be a good way to do it.

tmcalavy, I do understand your point about the center of gravity, but the primary purpose of this little boat is to be a bass boat with a foot-controlled trolling motor, etc. I can't do what I want to do without raised decks. Is there a way I can add raised decks without this kind of problem? I don't really care for the idea of removable decks. Thanks for the help.

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

One thing I may not have made clear that may or may not make a difference- I still plan on having a low floor at the center of the boat where the console goes, just raised decks in the front and rear, where you can stand and fish. The seating will be as it is now. Does that change anything about the problem of center of gravity?

 

[jameskb2]

Re: 15' tri-hull fishing boat rebuild, questions/updates

To understand this, think of the seats (I'm assuming post mount) as levers. The higher you put the seat in relation to the water line, adding a person as the counter balance weight, the more force there is on the axis.

So, a person sitting on a post mounted seat that is at deck level, and a person sitting on a post mounted seat at an elevated deck level will effect the roll or list of the boat differently. The higher the seat is mounted, the more that person shifting weight will effect the roll or list. Higher position of the weight on the lever (post seat) will create more force on the axis (water line)

I doubt it'll be a huge difference, it also depends on the beam (width) of the boat. Wider will handle horizontal loads easier than narrow.

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

OK jameskb2, thanks for the explanation. I do have a lot of experience with bass boats from 17-21' as well as 14' jon boats with casting decks, and I do realize the smaller boats can get tippy when you stand on them. This boat isn't super wide but it does have a wider beam than your average jon boat, and the tri-hull should make it more stable I'd think. I just was worried about performance problems while underway.

 

[jameskb2]

Re: 15' tri-hull fishing boat rebuild, questions/updates

Indeed.

The nature of a tri-hull is it's wide beam and relatively flat bottom to create stability. I think you have a good plan. Obviously there are many boats that are made in this manner. You said you have experience with Bass boats. As you know, a Bass boat has a wide beam and flat bottom affording increased stability. A narrow V hull is not as stable. Tri-hulls are kinda in the middle of the two.

I'd be sure that the weight of each deck is close to the same. This way you'll keep the bow / stern axis similar to what it was without the decks. If you build a huge heavy deck on the bow, and a light little deck on the stern, you could be plowing along and take water in wake dives. I wouldn't get crazy anal about it being exactly the same weight, but be aware that the boat has a center of gravity not just side to side, but front to back as well. Try to keep things even, and you'll be fine.

 

[oops!]

Re: 15' tri-hull fishing boat rebuild, questions/updates

yeah thats a tri hull, they are really stable, just build the upper deck light, and keep the gas tank low.

as far as the strip of plywood around the edge to rivet the cap to...... its just a small strip of lattice like wood.....thats easy to replace. it can be glued or resined into place.

that foams fun eh?......a freind of mine uses a wide blade pick to remove that stuff quick....

cheers
oops

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

that foams fun eh?......a freind of mine uses a wide blade pick to remove that stuff quick....

cheers
oops

I use a teenager Works much quicker than any tool I've found to date.

Thanks for all the info guys.

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

Friend of mine came over and we got a lot of good work done today, or at least a lot of good supervisin' and a little bit of work, since my broken ribs are still healing. We got the cap off and turned over, and secured on some 2x4s across sawhorses. My son did a great job cutting deck and digging nasty wet foam. Unbelievable how much that stuff weighs! We didn't find any more bad stringer sections. They are all rock solid everywhere but the one small bad section we found the other day. Here are a few pics.

 

[tashasdaddy]

Re: 15' tri-hull fishing boat rebuild, questions/updates

looks like you are ready for one of these.

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

Cool... what is that for, foam removal, or what? Where can I get one? I'm all about having the right tools.

 

[oops!]

Re: 15' tri-hull fishing boat rebuild, questions/updates

foam removal....those scrapers will take you right to the hull.....

after that ....its grinding time

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

foam removal....those scrapers will take you right to the hull.....

after that ....its grinding time

Cool, figured that's what they were for.

I know I'll need to do some grinding to finish removing the deck, cut the fiberglass to the edges, etc., but the stringers really are solid except for one piece of one of them near the rear, probably about a foot long section where it's kind of crushed. Everywhere else they are clean and sound like stone when you hit them with a hard object. We'll see how it goes as the stripping continues, I don't have blinders on and am willing to rip them out if I need to, but I really do think the stringers are ok.

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

So as I'm plugging along on the interior, I decided I should think about the finish. Figured I should probably at least do the bottom while the cap is off, and while the hull is gutted and light. The boat has a gelcoat but it's not in great shape. I've searched enough to learn that you can paint over gelcoat, I just wondered what you guys might do with this boat.

I want to keep it white, except I'd like to make the blue stripe red, which means I'll have to sand down the blue metal flake. I have no spray equipment, do you guys think this should immediately rule out gelcoat and that I should stick with something like Perfection? Can you still do metal flake with brush-on/roll-on paint, or would I be stuck with a solid red stripe instead of red metal flake?

Here's a pic of the side to show the color, taken when I first got the boat.

 

[brian3127]

Re: 15' tri-hull fishing boat rebuild, questions/updates

i dont know about the paint but im doing the same thing you are already pulled old floor and foam out all rotted and soaked took it to the city dump and it weighed 700bls so yeah there is alot of weight there in soak floor and foam i have pics of my work so far post on here if you want to go and look titled (pics of my boat project)

 

[i386]

Re: 15' tri-hull fishing boat rebuild, questions/updates

I have no spray equipment, do you guys think this should immediately rule out gelcoat and that I should stick with something like Perfection?

It's been said that spraying gelcoat isn't a skill, it's an art. Then, once it's on you'll have many hours of sanding, polishing, and waxing to get the finish you want.

If you want to study up on gelcoat, there was a member here a while back called "neat". Search for his posts on gelcoat. From what I can tell his gelcoat job looks really good. I haven't the equipment or experience to try it. It's polyurethane topside paint for me and my trailer queen (boat, not wife lol).

This one for example: http://forums.iboats.com/showthread.php?t=179450

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

Cool Brian, I'll go check out your project now. i386, I figured as much. I don't know why the first reaction is to want to gelcoat, for a lot of people... but I have no business attempting that right now. My friend had great results with Interlux Brightside, and I have been reading great things about Perfection here on iboats. I'll do my best to level and smooth the existing gelcoat, and fill where needed, and then get something from Interlux.

i386, just curious... how did you get your nickname? Are you a fellow IT guy?

 

[Hydrilla]

Re: 15' tri-hull fishing boat rebuild, questions/updates

...but the stringers really are solid except for one piece of one of them near the rear, probably about a foot long section where it's kind of crushed. Everywhere else they are clean and sound like stone when you hit them with a hard object. We'll see how it goes as the stripping continues, I don't have blinders on and am willing to rip them out if I need to, but I really do think the stringers are ok.

I can picture you guys reading this, starting to type, and then telling yourself "never mind, I'll let him find out on his own." Well, I did. The stringers have got to go. They ARE solid... 2/3 of the way up. The top 1/3, or maybe 1/2 in some places, has rotten wood. I gotta do this right, no cutting corners.

Spent a few hours today hacking up foam, ripping out the rest of the inside skin of the transom, and cutting some more deck out.