transom questions

[natchalkley]

so I am in the process of replacing the transom on my 23cc. I go the core in last weekend and today I started with glassing it in. I thought I knew what I was doiing but now I have a question. I saw that Strick did 2 layers of 1708 on his 20cc, so I figured that that was what I needed to do on this. Now today I read a post that says I need 4 layers here instead of just 2 . I am planning on putting a 300 Suzuki on probably an Armstrong widebody bracket w/o the platform(want to leave the option of cutting in a transom door at some point). I was planning on having a full backing plate made for the inside of the transom to distribute the load more evenly.
what im getting at is: should a put 2 more layers of biaxle(1808) on the inside and skip the backing plate or should I go with my original plan? I am planning on putting 3 swivel rodholders in the transom for Giant tuna fishing so I dont need to support a livewell or anything.

[BigLew]

I've got a question.

Will two layers of 1708 with a bracket and the weight of a 300 Zuke leveraged off the transom be strong enough if/when you decide to add the transom door?

[JohnB]

I wouldn't say it is or isn't enough. I consulted a marine archtect before I did mine, and I would suggest you do the same.

My pure guess is between the bracket and the weight of the motor, your more than doubling the load on the transom. If it was mine, I would have 4 layers, and then beef the corners, since that is where most of the load will be concentrated. Are you using coosa/composits or plywood?

[htillman]

Your are correct talk to an expert. With fiberglass you need some engineered flex or your going to get fatigue cracks over time.

[strick]

On my 20 the old transom consisted of the outer skin (1/4" thick) 2 pieces of plywood nailed together without any glass in between and 1 layer of woven roving for the inner skin. That transom lasted over 30 years. After seeing that I went a little lighter then I would normally go with the glass. There is 1 layer of woven roving and 1 layer of 1708 on the inner skin of the 20's transom. For a 23 with a big block V6 I would go no less then 3/8 inch thick glass on the outer skin and the inner skin about 1/4 inch thick glass. Each layer of 1708 will give you 1/16 inch thickness. Put a layer of 1708 and between the cores and between the core and the old glass on the outer skin with thickened cabosil to ensure a good even bond. Remember that the transom is also strengthened by the transom cap when you add that down the road.

strick

[Bigshrimpin]

Nat - Did you use Epoxy or Polyester? Epoxy will blush when cured, so if you plan on adding more glass make sure to remove the blush first. I think with backing plates and some support knees you will be fine with the two layers. My 20 I/O was the same 1/4" to 3/8" Thick outside an 1 layer of mat and roving inside. It's the original transom from 1972 and it's holding up fine with the new 200+lb bracket I built.

forget about the door and just use an "A" frame.

[natchalkley]

Strick:
I already have the core glassed in at this point. like you said, I did put a nice think layer of cabosil around the edges and in between the skin and the core; however, I didnt put a layer of biaxle inbetween the 2 pieces of 3/4 marine play. instead I used a coating of cabosil and gave it some texture with a ridged tile trough. and screwed/clamped/put bricks and cinder blocks down on top of it.

bigshrimpin:
I decided to go with epoxy. I have never used polyester before and I knew that might be doing a lot of the work in some colder weather. that combined with my experience using epoxy(6 years maintaining wooden boats at WH yacht club, and having to replace the gas tank and rebuild a lot of my parker 21 SE last year) lead me to go with epoxy.

I am planning on putting knees in on either side of where the bracket will be mounted, and now will probably put at least one more layer of glass in there. the added strength will greatly out-perform the little bit of extra weight.

I now have another question: I have to flip the boat to work on the bottom. my plan is to either to it with jacks and comealongs or to use a tractor with a front end loader on it. I am obvioulsy going to put the gunwhale cap back on, but do I need to support it more side to side. I saw a couple of years ago a guy used a towtruck and I am wondering how this worked for him.

[natchalkley]

Strick:
I already have the core glassed in at this point. like you said, I did put a nice think layer of cabosil around the edges and in between the skin and the core; however, I didnt put a layer of biaxle inbetween the 2 pieces of 3/4 marine play. instead I used a coating of cabosil and gave it some texture with a ridged tile trough. and screwed/clamped/put bricks and cinder blocks down on top of it.

bigshrimpin:
I decided to go with epoxy. I have never used polyester before and I knew that might be doing a lot of the work in some colder weather. that combined with my experience using epoxy(6 years maintaining wooden boats at WH yacht club, and having to replace the gas tank and rebuild a lot of my parker 21 SE last year) lead me to go with epoxy.

I am planning on putting knees in on either side of where the bracket will be mounted, and now will probably put at least one more layer of glass in there. the added strength will greatly out-perform the little bit of extra weight.

I now have another question: I have to flip the boat to work on the bottom. my plan is to either to it with jacks and comealongs or to use a tractor with a front end loader on it. I am obvioulsy going to put the gunwhale cap back on, but do I need to support it more side to side. I saw a couple of years ago a guy used a towtruck and I am wondering how this worked for him.

[Bigshrimpin]

That's a good question for strick. His buddy with a tow truck flipped his boat . . . I don't think they added any support, but it's better to be safe than sorry.

[strick]

We did not flip it just picked it up and set it on stands. I would think the cap should keep the hull true but I guess it just depends on the condition of the boat.

The core should be OK even though there is no biaxial in between each piece.

Strick