Question about repair on my trihull

[f4igrad]

my boat has always taken on just a little bit of water, but nothing to be alarmed about. it had a crack in the hull that i fiberglassed, and I am about to start pulling up the floor to check the stringers and add more fiberglass to the area that I originally repaired, hopefully making the boat completely water tight. <br /><br />the last time i was out, the water was very choppy and slapping up against the boat (1975 trihull, rides low on the water). the boat was taking on water much faster this time, so fast that I pulled it from the water and haven't gone back out. I have noticed that the seam where the top half and bottom half of the boat meets has a lot of caulk that is gone or deformed. could the waves be splashing up into the seam and causing water to enter the boat? <br /><br />One last questions: once I pull up part of the floor and fiberglass more of the area around the original crack, can I go and put the boat in the water to visually inspect for any areas where water is leaking in?<br /><br />thanks everyone!

 

[f4igrad]

Re: Question about repair on my trihull

ok<br />another question. i just ripped out most of the floor of the boat. all 3 stringers are rotten. my wife and i are only planning on using the boat for the next couple of years as we get our finances arranged, then we are going to buy a newer boat with a bigger engine. because of this, I want to do a repair that doesn't have to last 20 years. can I just rip out the floor, then add new stringers with a layer of fiberglass around them, then layer a new floor back on top? i am thinking about even leaving the old stringers in...i don't care about the weight. <br /><br />i understand that a lot of people are perfectionists and want their boat to be in perfect condition, but for a boat that I will only have for a few more years, I am not too concerned about that. i just want to invest as little money in it as possible.<br /><br />thanks a lot, i appreciate the replies.

 

[f4igrad]

Re: Question about repair on my trihull

^

 

[JasonJ]

Re: Question about repair on my trihull

You don't have to spend a ton of money. Skip the epoxy and marine ply, thats where you spend a lot of money. Use polyester resin, and a/c ply. Go to local boat repair places, not stores. Buy the resin in bulk from the repair shop, they'll sell it to you cheaper. They can also sell you the mat and cloth as well. Find the cheapest lumber yard in your area and buy the ply. I went as cheap as I could on my rebuild, and I still ended up spending something in the neighborhood of $400-500-ish fo materials, yours may be less.<br /><br />Now, the rebuild. Remove all rotten wood. Using a 4 1/2 inch grinder and cutoff wheel remove all old stringers, glass, all of it. Put a grinding wheel on the grinder, and rough up the areas you are glassing to. Using acetone or (preferably) styrene, wipe down the areas to glass. Replicate the original structure, glass it all in with mat and roving, call it good. I was being very vague, find books or do a search for a more complete description of the process.<br /><br />Also, make sure you find and fix that leak. As far as perfectionists, its not a matter of being a perfectionist, its a matter of building a safe boat. You are taking you family out on it, you want it to be sound. Cutting corners isn't a good idea. Some will say epoxy and all that are the only way to go. They are wrong. The expensive route gives you a great rebuild, the normal route gives you a rebuild that will last longer than the original build. If you are wanting the boat to only last a few years, you could try to cobble it, but you could end up having the boat fail and that would be bad. Safety first, economy second. Good luck...

 

[f4igrad]

Re: Question about repair on my trihull

so if i don't remove the old stringers but I add new wood, what is the worst that could happen?<br /><br />also, if I didn't completely glass in the new pressure-treated wood, but instead just glassed it securely to the boat, how long would it last?<br /><br />thanks for the reply!

 

[f4igrad]

Re: Question about repair on my trihull

hmm, i just came across this old post and I am thinking about trying this method. I could just add a ton of mat to the existing rotted stringers to regain the original rigidity.<br /><br />"Throw a few layers of 'glass' over the rotted area and move on.<br /><br />Some boats used to be made where the stringers were hollow. The builder put about 1/8th" of fiberglass mat over a wooden 2 x 4, then when it had set, pulled the board out and put the stringer in the hull with a layer or two of fiberglass mat over the molded hollow rectangle that they pulled off the board. That was their stringer.<br /><br />There is nothing majic about the wood being in there. If its rotted and structurally worthless, you can just overlap it with a few layers of 'glass & resin to regain the structural strength it used to have.<br /><br />It would save a pound or two if you could get the rotten wood out first, but if that isn't a big deal-- leave it. The layer or two of fiberglass overlaying the rotted core of the stringer will give at least as much strength as you lost when the wood rotted.<br /><br /><br />The stringer gets its strength from the sides & top/bottom in resisting a 'bowing' load like a piece of square tubing. Or, when its new, its more nearly like a solid bar. <br /><br />If the bottom is the hull, the center is filled with wood-or whatever, then the top can be sort of thin. The rest of its strength is made up by the sides... Like a square pipe.<br /><br /><br />Here's my logic on adding 'glass to the sides & top:<br /><br />If the bottom of the 'tube'- or stringer (the hull)is sound, and the center (the wooden board)is essentially gone,,,,,,,,,,,<br /><br />Then, the lost strength of the 'missing wood and the 'thinness' of the existing top, can be made up or even exceded by strengthing the sides & top. <br /><br /><br />This has worked for me on a few Fiberglass hulls I have had in years past. But don't tell anyone I recomended this, or I will lie and deny everything. When the pureists see this, and start pounding their pitchforks on the ground and lighting thier torches in preperation for buring us at the stake---- I'll point over,, and blame it all on you. <br /><br />Ed."<br /><br />taken from this thread: http://forums.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=26;t=002368#000001

 

[tashasdaddy]

Re: Question about repair on my trihull

you've said it rides low in the water, you're carrying wet wood and foam. and you just want to add more weight.

 

[f4igrad]

Re: Question about repair on my trihull

there is no foam in my boat, and it will only hold two people most of the time (it is built for 6). I figure the wet wood is about the equivalent of a cooler full of beer.

 

[Solittle]

Re: Question about repair on my trihull

If you are looking for our stamp of approval to jury rig a boat with a 31 year old cracked hull that leaks and has rotten stringers (that you want to do a Mickey Mouse repair) - - - sorry but count me out. <br /><br />I suspect that you will do what you plan -- If you do make sure that you have your will up to date. Your family hopefully won't need it but if they do - - - -

 

[f4igrad]

Re: Question about repair on my trihull

geez, can we be a bit more dramatic?<br /><br />Everyone says to use the search engine...well I did and I found this post from a SENIOR MEMBER that explains, in detail, why this method would work. Then several other SENIOR MEMBERS agreed with him. I am just asking for some opinions, to see if anyone thinks this wouldn't work, and why. You can keep the "you're gonna die" crap to yourself.

 

[ondarvr]

Re: Question about repair on my trihull

It can work, but it sounds like you have other problems with hull integrity also. except for the wood, the cost will be about the same, so you don't save much money. You will still need to clean and sand (grind) everything very well and then reglass using mat and roving, a little more glass than if you had new wood in it. Check to see if there is enough room to add glass to the top of the old stringers, you will need to add glass to the top of them and your floor may not fit back in the same place when you do. You can cut them down some before you start glassing so you will have the needed room, but then you might as well take them out and replace them.<br /><br />It's not going to work on every boat and it's not the recommmended method of repair, but can work in the right situation.

 

[f4igrad]

Re: Question about repair on my trihull

thank you for your response. i have a ton of cloth, but I guess i need to buy some mat as well. the boat actually felt pretty solid, considering the state of the stringers. I could jump up and down on the floor and it was totally fine, except for a small spot under the driver's seat. the crack in the hull is right alongside one of the rotten stringers, so it is evident that the flexibility of the stringer caused the crack to form. i am going to patch it very carefully before i start working on the stringers.<br /><br />i have the entire floor up now, and it is such a small boat that there isn't a lot to worry about. it only has 3 stringers in it, one main keel and then two small stringers, one on each side. There is no foam whatsoever, so i didn't have to clean that up.

 

[ondarvr]

Re: Question about repair on my trihull

Cloth is not very srong when compaired to roving so you will need to use more of it.

 

[AMD Rules]

Re: Question about repair on my trihull

f4igrad,<br /><br />There's something in the air around here these days. People are getting agitated when other's ask questions. Any chance you have a picture of your boat strpped down in its current shape? Picture of the crack that was mentioned?<br /><br />There's many , many people out there who just slap on another layer of plywood over a completely rotted floor and get another season out of it. Obviously its won't be recommended on a boating restoration forum. I'd congratulate you on removing the floor. That was a wise choice.<br /><br />The decision to leave, or remove the old stringers isnt really one of cost. I'd say remove them. They'll only get in your way when you put the new stringers in.<br /><br />Stringers with only strips of glass over them - Munro factory circa 1980<br /><br />My old hull had the stingers exposed, and only tabbed in to the boat every couple of feet or so. While its not ideal, it lasted 20 years from the Munro factory that way. Maybe you could just coat the stringers in epoxy , and adhere it to the hull well in several places.<br /><br />If you don't want to keep the boat, spend more time and money making sure the stringers and deck are adhered to the boat, and don't worry so much about protecting them from rot. Just be honest to the next purchaser when you sell it.<br /><br />How's the transom?

 

[Tail_Gunner]

Re: Question about repair on my trihull

As to the foam question this a very simple question and answer. Using a closed cell completely fillings all the void's is perhap's the best way onc can prevent water intrusion. <br /><br />Simply stated if there is no potential for mass (water) then there can be no rot. That is if you have taken reasonable steps to seal any exposed wood that could absorb a small quanity of water you cant go wrong.<br /><br /> Most of the boat's you see here are of old design and along with change comes time and in time closed cell foam will replace wood.........I am amazed it has (wood) has lasted this long ........the boating ind is still holding on to old memories.

 

[f4igrad]

Re: Question about repair on my trihull

thanks again you all. i guess the reason why i am interested in just bulking up the existing fiberglass over the old stringers is because i have a very bad back, so bad that I feel like i can't move at the end of a labor intensive day. pulling up the floor resulted in an afternoon of laying in bed and heavy ibuprofen dosages. i am afraid that pulling up the stringers will be very labor intensive and will once again ruin my back for a couple of days. applying fiberglass and epoxy shouldn't be quite as bad and might not put me in traction. i am going out today to grind down the old glass around the crack and repair it with cloth, mat and epoxy. After that I am going to go float the boat in the lake and see if there are any areas where water is entering. <br /><br />Once I know the hull isn't leaking, I will reinforce the stringers and put a new floor back on, although I won't epoxy it for a couple of days so I can take the boat out check for water intrusion.<br /><br />Finally, this boat is not used for skiing, tubing, or any other high speed type of activity. We don't even take it out and buzz around the lake at high speeds. It is basically a swim platform so my wife and I can go out and enjoy the lake, lay out and read a book, float in the water, maybe have a sandwich and a beer. So, the hull isn't exposed to the types of pounding that most boat hulls have to handle.<br /><br />Thanks again for the opinions, if you all have any other suggestions I am open to hearing them.

 

[f4igrad]

Re: Question about repair on my trihull

just an update to my project:

I spent all day today on the stringers. I decided to split the difference between popular opinion and the theory stated earlier in my post, so I bought several pieces of wood and reinforced the existing stringers with the new wood. I epoxied quite a bit of mat and cloth to the new wood and the existing stringers, and the bottom of the boat feels MUCH more solid than it did before I started. I have also ordered some foam, and I am going to fill all of the voids with it. i feel this will reinforce the floor and hull even more.