76 magnum trihull full project

[CapPhil64]

Didn't mean for that to come off so rough. Sorry, I was just trying to state the size of the project. And I talked to my fiberglass guy about 1708 and he said that just a few layers of this 24oz roving would be fine to do if you do it all at once. He never mentioned putting CSM between the layers. Again just to state I don't intend to completely waterproof everything i have treated lumber that i have treated myself on top of drying it for months and I don't intend on this boat to haul ass or anything, so is it necessary to sand-which CSM between my WR sheets? everything i have put down to the hull on two layers of WR has held together magnificently

 

[Woodonglass]

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I can't emphasize enough the need to use CSM when using poly resin. Poly has NO binders in it's chemical makeup. Therefore when it cures it will become very hard and brittle. Using just the WR with the resin will appear to be holding together well now but...When it flexes it WILL break and crack and then allow water to penetrate as well has destroy the structural integrity of the bond. Poly contains Styrene and the Styrene Breaks down the fibers In the CSM and thus "Binds" the resin molecules together making the resin a homologous unit. Very important that you use it. Don't know who your Fiberglass guy is but he should have known that. I've included a link that clearly shows/talks about this. 1.5oz CSM is the recommended weight to use with the 24oz WR. IMHO 24oz is OverKill for your boat. 18oz would be more than adequate and as I stated the 1708 IS much easier to use (again my opinion) and not just for Speed Boats and such. Most of the restorations on this forum utilize this material. Do you know the name of the MFG for your resin? Do you know if it contains wax?

This is a post from our resident "Expert" on Polyester resin and layups. ondarvr has over 40 yrs experience in the business.
http://forums.iboats.com/forum/boat-...05#post2834905

http://forums.iboats.com/forum/boat-...56#post2831756

 

[kcassells]

Cap.. Welcome aboard! How did you test the transom for integrity?

 

[52FordF2]

You stated you got this off the side of the road, got title? You may want to get it titled first before continuing.
Just my $0.02 worth.
keep up the work.

 

[jigngrub]

I cut the glass off of the transom to evaluate its structural integrity and to inspect for rot. the transom is two 1/2" plywood boards resined together. I'm using poly-resin for my build.

Did you remove the entire inner skin, or just the edges? Was your transom wet?

I personally would do the transom too so everything would be brand new. but that's prolly just me.

 

[gm280]

Well now I confused somewhat. You initially listed your boat as a full tri-hull project and stated: "Tell me what you think and I gladly take friendly advice!!" in your first post. But then you seem a little resentful or offended when advice was offered. So are you really needing such advice or are you just wanting to show everybody your project. Those are two different things? Remember we are here to offer rebuild info and how-to's for what your are undertaking. So if you really want advice, let us know. But don't get offended when information is issued. Not one of us knows what your abilities are and so we go by a known successful sequence of steps to help first time folks refurbish fiberglass boats. Actually the same advice we offer everybody that asked for it... So again if you honestly want anybody's advice on here, as it seemed you did ask for initially, let us know... We are not mind readers...yet!

 

[CapPhil64]

You stated you got this off the side of the road, got title? You may want to get it titled first before continuing.
Just my $0.02 worth.
keep up the work.

I have the title in my name already. That was the only reason i was okay with picking it up so easily. Smooth transaction.

 

[CapPhil64]

I didn't mean to sound resentful for receiving information. I tried to make that clear. I appreciate the info but for the stringers they are already in. I was asking for info on tabbing the deck in. If i wasn't building a speed boat would it be okay to use the combo of fiberglass and resin i am using.

 

[CapPhil64]

And clearly i need to use CSM So i will go grab some of that to finish up what i need to. Thank you for the info!!

 

[CapPhil64]

Did you remove the entire inner skin, or just the edges? Was your transom wet?

I personally would do the transom too so everything would be brand new. but that's prolly just me.

I decided that the fiberglass and wood wasn't going to break underneath the pressure of motor and twisting it. I cut the inner skin off of the transom to check it for water damage. everything seemed ok. I plan on glassing back over that and making sure that this boat will be able to simply cruise before i do a deeper restoration. My motor is running but i want to make sure it will run under pressure and do the job before i invest more before this season. I will be driving a ski boat this summer almost 24/7 for work so im trying to get this thing ready to dunk in the water and float around in the evenings to relax.

 

[CapPhil64]

Cut out my front platform seat while the weather was down here and couldn't play with resin. Should I resin the board if i am going to wrap top with vinyl? Could I just paint it?

 

[jigngrub]

I decided that the fiberglass and wood wasn't going to break underneath the pressure of motor and twisting it. I cut the inner skin off of the transom to check it for water damage. everything seemed ok. I plan on glassing back over that and making sure that this boat will be able to simply cruise before i do a deeper restoration. My motor is running but i want to make sure it will run under pressure and do the job before i invest more before this season. I will be driving a ski boat this summer almost 24/7 for work so im trying to get this thing ready to dunk in the water and float around in the evenings to relax.

Ok, mine are just suggestions and I'm not offended if you don't take them. Since you already have the stringers tied back in I can see where it would be a major pita to do the transom now. I only suggested redoing the transom whether it needed it or not because I consider the transom of an outboard motor boat the most important part of the boat and they aren't very expensive to replace. 2 sheets of plywood and some resin and glass, maybe about $100 +-. And since you already have the cap off, the deck out , and the boat is open....

We've seen 1 or 2 members on here incorrectly determine their transom was good and chose not to replace it only to came back a year or 2 later to have to tear their nice pretty resto work apart to put in a new transom and you could tell they were kicking themselves for not doing it the first time. Maybe this won't be the case with you.

 

[Georgesalmon]

A little late here but I want to possibly correct some confusion about Woven Roving. Back a while ago I built many Rib boats for our US Navy as replacements for the old motor whaler boats used since WWII. The contract spec called for 6 layers of 24oz WR on the hull bottom after the skin coat, NO mat in between. After winning the contract at our first contract meeting I questioned that there was no mat between layers of WR and was worried about delamination. The Navy Fiberglass expert told me that they had done extensive testing on just that subject and that the interlaminar shear results were the same or better with out mat between the WR. During the contract we had to send many samples of each hull out for testing at an independent lab. The results of those tests showed that this was all true. There is no benefit to using mat between layers of WR unless you want to increase the thickness cheaper than more layers of WR. Just an FYI.

I also tried to talk them into using a knitted fabric such as 1708 and was told that the stiffness was just where they wanted it and we would have to use more of the knitted fabric to achieve the same flexural modulus. Also the added expense didn't gain them anything. There is really more to it but talking the navy into anything new when they have something that works is very difficult with good reason. There are lives at stake, they can't just stay home when the weather is bad,,,,,

 

[Woodonglass]

Uhmm George what was the SIZE of these hulls and was this only a Flat Lamination and not one with a 90 degree bend such as tabbing stingers to the hull. I truly respect your experience and knowledge and am wanting to learn. Did you actually SEE the results of these tests and laminations? Did you do any follow up to see if the layups were actually successful. 6 layers of 24oz WR would build up a real thick hull very quickly. Sounds like they were looking for bulk and weren't to worried about waterproofing the laminate. Sent to independent lab, UH HUH Wonder what YOUR TESTS would have produced!!!! The comments about Lives at stake and the Government is really a moot point. To many examples of that NOT really being pertinent!!! :blue: Remember You CAN'T SUE the Gubbament!!! I know the Government does things a bit differently at times sometimes for the better and sometimes NOT!!! Just don't quite understand how the Styrene in the resin could molecularly and chemically work correctly since it won't break down the fibers in the WR and it will in the CSM. the WR will hold the glass together like rebar and concrete but it would still be able to crack and break. The breaking down of the CSM fibers by the Styrene renders the resin more flexible and less likely to break under duress. With out the CSM, under stress and Flex wouldn't it Break and Crack. I'd really like to see some of their research and testing. But if this really is true, for CapPhil this is GREAT news. Sounds like his stringers will be fine. I'm still a bit skeptical. Looks like I've got a lot of research to do before I can recommend using WR without CSM!! (No offense George)

 

[CapPhil64]

A little late here but I want to possibly correct some confusion about Woven Roving. Back a while ago I built many Rib boats for our US Navy as replacements for the old motor whaler boats used since WWII. The contract spec called for 6 layers of 24oz WR on the hull bottom after the skin coat, NO mat in between. After winning the contract at our first contract meeting I questioned that there was no mat between layers of WR and was worried about delamination. The Navy Fiberglass expert told me that they had done extensive testing on just that subject and that the interlaminar shear results were the same or better with out mat between the WR. During the contract we had to send many samples of each hull out for testing at an independent lab. The results of those tests showed that this was all true. There is no benefit to using mat between layers of WR unless you want to increase the thickness cheaper than more layers of WR. Just an FYI.

I also tried to talk them into using a knitted fabric such as 1708 and was told that the stiffness was just where they wanted it and we would have to use more of the knitted fabric to achieve the same flexural modulus. Also the added expense didn't gain them anything. There is really more to it but talking the navy into anything new when they have something that works is very difficult with good reason. There are lives at stake, they can't just stay home when the weather is bad,,,,,

Thank you for your input and helping to try and clarify what we were wondering about the WR being used by itself. I will surely keep everyone posted on how my fiberglass job holds up after i get the boat in the water. We can qualify those as lab results, right?

 

[CapPhil64]

Ok, mine are just suggestions and I'm not offended if you don't take them. Since you already have the stringers tied back in I can see where it would be a major pita to do the transom now. I only suggested redoing the transom whether it needed it or not because I consider the transom of an outboard motor boat the most important part of the boat and they aren't very expensive to replace. 2 sheets of plywood and some resin and glass, maybe about $100 +-. And since you already have the cap off, the deck out , and the boat is open....

We've seen 1 or 2 members on here incorrectly determine their transom was good and chose not to replace it only to came back a year or 2 later to have to tear their nice pretty resto work apart to put in a new transom and you could tell they were kicking themselves for not doing it the first time. Maybe this won't be the case with you.

I do plan on replacing the transom completely after i get a season under the motor and make sure it can hold up. I left space in the back where the old deck is in the pictures. I plan to just cut that piece out and tie a bulkhead in to two runners like it is set up now and glass that all to tie into the stringers i have put in. If you have any input on my best bet to pull that off that would be extremely helpful. Thanks for your input you are helping me understand how important this transom job can be for me.

 

[CapPhil64]

No Title

 

[CapPhil64]

No Title

Everything look good for the way I had this laid out?

 

[Georgesalmon]

Yes, I did SEE the results on over 60 hulls. The hull shape was V bottom, and the WR did make a nearly 90 degree bent at the chine and of course it was curvy all over with lots of compound curves. Actually I think WR is easier to use on those. It will move in the weave unlike material that id sewn together with polyester thread. Anyway, I was just reporting on something I had done I the past not trying to make trouble. The glass "rovings" in the woven roving are pretty much the same as the rovings that are chopped up when making CSM and CSM has much more binder in it than the woven roving has because that's what holds it together. The WR is held together by weaving it instead. Now, I'm not saying that its better than knitted fabrics. If using the same weight per sq yard of WR and knitted fabric the knitted will be thinner and use a bit less resin per sq yard. That accounts for an increase of tensile strength but a decrease in flexural modules because it will be thinner.

This was a 24' hull with 8 pound polyurethane stringers also covered in 4 layers 24oz WR. Had a diesel engine mounted under the center console with about a 4' shaft back to an outdrive.

 

[Woodonglass]

Kool! Good Information. Not trying to cause trouble either. Wanting to learn too!!! I used WR way back when I was a Youngster working in a Marina. Found it to be Very hard to work with and used a lot of resin but was told to ALWAYS use CSM due to binders. The old guy that taught me was adamant about that. That's why I was asking! Thanks for the description. Do you know what those boats were used for?