The subject is a 74 20 cc with some problems
 

hey everyone im new here great to see such dedicated people to there Seacrafts. Ive been checking this site out for a while now and have a few questions since ive finally comenced on the project. The boat i have of coarse needs the works. Im pretty set on using a composit for the floor and transom. my concern is are there any brands that are better to use for a transom verses a floor. Ive been looking at Divinecell just because thats what the local supplier carries. Is there a common concensus on any one product?
Trayder I noticed you used Nida core product. How was working with it any pluses or minuses? I appreciate everyones insite. THANKS

This website is probably the best tool available for redoing a seacraft outside of a good grinder and a case of beer!! [img]/images/graemlins/wink.gif[/img]

Re: The subject is a 74 20 cc with some problems
 

Some guys over on the Classic Mako board have been glassing in a single 1.5" thick sheet of Coosa Bluewater 26 board in their transoms. So far, they have been very happy with it.

http://www.coosacomposites.com/bluewater.html

That is what I will be using in my transom when the time comes.

Re: The subject is a 74 20 cc with some problems
 

Hey thanks for the tip gw204, I called the company and they stock this stuff out of annapolis md. This stuff has to be pretty tuff stuff It is basically a product like divinecell with layers of roven imbedded through out. I priced a 4x8 sheet at 1 1/2 inches thick of bluewater 26 . After I scraped my self of the floor I came to relize that I did here the price correctly it was $580 plus shipping if your not local. Its still one of my choices. I have them sending me some samples so i can see exactlly what im getting. But if any one has priced this product for cheaper If you could please let me know where id appreciate it. thanks again GW [img]/images/graemlins/wink.gif[/img]

Re: The subject is a 74 20 cc with some problems
 

If your original transom lasted 30 years laminated in polyester resin and with transducer holes.

Why wouldn't you consider marine plywood for the transom?

If you use epoxy and refrain from drilling holes in the transom or even if you seal them properly, you're new transom should last longer than the original.

how old will you be in 30+ years?

Re: The subject is a 74 20 cc with some problems
 

I agree with BigShrimpin, but oddly enough, I was thinking of using a composite on my 23 with a full transom. My thought is to keep the weight down. Still looking at that option, but will go with wood again if the savings isn't that great.

My research so far has been that Plywood weighs 25 lbs per 1/4 inch on 4x8 sheets. That coosa stuff would weigh 69.3 lbs on a 4x8x1 sheet. The weight savings just isn't there for me at that cost. On my 20 project, my supplier scolded me for even thinking of using composites.

FYI, be careful of using 1 1/2" material. The original thickness was 1 3/8. You may have a hard time refitting that splash well if you go thicker. I had this problem on my 20 sceptre.

$580 bucks? I would find another product. Nida Core is about $170, but would it be good for a transom???? How easy is it to fill the edges with goop?

Re: The subject is a 74 20 cc with some problems
 

After having done 6 Seacraft 23 transoms in the past 2 years for customers, I think that plywood is still the best all round solution. The only thing we do different than most people is to mark the motor bolt holes before the exterior glass goes on and put in 4" diameter cores of Divinycell H100. If it was my own boat and cost was not an issue,I would use the H100 or H120 for the whole transom. As far as Nida core goes, it will work for a transom. But the glass skins will have to be thicker and there will be no advantage to using it. Also on the subject of saving weight. You always have to remember, if you lighten a boat from it's design weight, the ride changes. We have build boats very light compared to design weight for customes looking for speed, but to it always backfires when it comes to ride quality and handling. One Seacraft we modified by removing near 800 lbs rode like crap and pounded in 2-3 ft seas. It would also layover onto a hull flat if you did not use the tabs going straight. Now when it was loaded to go tuna fishing with full fuel and 1000lbs of ice. It behaved like a Seacraft should.
Just my 2 Cents.
Bill

Re: The subject is a 74 20 cc with some problems
 

Ha Bill
Thanks for your input on this topic. I did my transom with wood and if I was doing it for a business I can see why plywood is still the way to go, wanting to keep the costs down. I also like what you had to say if you were going to do it for your own boat and was going to keep her for a long time using Divinycell. Plus your comment of weight, it seems that most people think liter is better but for me heavier is better as long as it is properly distributed in the boat.
FellowShip [img]/images/graemlins/wink.gif[/img]

Re: The subject is a 74 20 cc with some problems
 

Just redid my transom w/ plywood. It is the way to go. Strong, cheap and EZ. If you seal everything correctly - you will have no problems.

Then, if you want to - where you are going to bolt through or screw through the transom, - drill out these areas w/ an oversized hole saw ( from the inside not going thru the gelcoat skin ), and remove the 'round' pc of wood.

Fill this round, voided area w/ a mix of West System epoxy and cabosil, place duct tape or a thin, temporary pc of plywood 'patch' over it till it cures. Then, from the outside ( the gelcoat side ), drill your thru hull through this epoxy. Bed your thru hull, and you will have no problems w/ rot 'cause all thru holes will go thru epoxy not wood.

alan

Re: The subject is a 74 20 cc with some problems
 

abl111,
How large of a hole do you need to drill (the oversize hole). Would you go 4" diameters if not using a core material such as divinycell like Bill used. Also, do the motor mounting washers on the inside of the transom need to be larger than the oversized hole you previously filled with cabosil and epoxy.
Thanks -Will

Re: The subject is a 74 20 cc with some problems
 

I used the Coosa bluewater for my transom, I laminated 2 3/4 in pieces together with epoxy and the white thicking product( brain fart I cannot think of the name of the product).
It came out nice, I live in Annapolis, yes the product is expensive, but It will never rot, or absorb water. I did call the company, just to check on the strength of the composite, as my rig is an I/O, He said 100 % of all the new boats are made of composites, just don't over toeque the transom mount for the OUTDRIVE.
Just my 50 cents worth.
Good luck,
JW

Re: The subject is a 74 20 cc with some problems
 

Will that's a damn good question ! I have an I/O and did not have to worry about bolting an outboard thru the transom.

I cannot answer your question because I do not know how the epoxied holes would handle the strain of an outboard motor. The epoxy is string as sh_t, the larger washers seem like a good idea; but I would not do anything like what you're talking about until I got a solid confirmation from someone who is 'in the know'.

Actually, rather than the washers, I would think that (2) 1/4" stainless plates or (4) 4"x4" stainless plates would give a lot more support than the washers.

It is an interesting question though - anyone have an opinion ?

Re: The subject is a 74 20 cc with some problems
 

The proper backup washer or backing block can only be determined by the comperssion strength of the core material and the thickness of the fiberglass. Some of the most common errors made by people are the use of square washers and round washers that are too small. No matter what size you use, make sure that some type of bedding compound is used. This is most important with square backing plates as the corners have a habit of cutting into the laminate and causing faliures over the long term.
Bill

Re: The subject is a 74 20 cc with some problems
 

Great comments ...and guess I'm old school

WOOD IS GOOD [img]/images/graemlins/grin.gif[/img] [img]/images/graemlins/cool.gif[/img] [img]/images/graemlins/grin.gif[/img]

I am curious to see how these composites hold up over the long run ....But it is somewhat daunting to see damage to these composite hulls that are only a few years old [img]/images/graemlins/frown.gif[/img]

Re: The subject is a 74 20 cc with some problems
 

Thanks everyone for your imput I guess I found the common concensus is to go with wood. I read an article that was saying that the delamination factor is greater with a composite,sounds like the resin bites into the wood a little better. Has anyone ever seen this on boats, Ive seen it on surf boards. Well I guess Ill be leaning towards wood, Question though what type of plywood should i be using I heard people say Marine grade Plywood. where do ya get this stuff? Is this the stuff at Home depot treated with cca? thanks again

working on the single boat theory.. [img]/images/graemlins/grin.gif[/img]

Re: The subject is a 74 20 cc with some problems
 

Any good lumber yard should be able to order marine grade plywood. Don't use any other type of plywood as the glues used to make it are not as strong. Also the quality of the plys and void content is better. As far as the resin "biting into the wood better", that's not really true.
Most failures can be attributed to improper use and application. I can go on about this for hours after 30+ years of boat building and repairing. If you have any specific questions, just ask.
Bill