Transom Help Needed - 1975 Tri hull

[sramos]

Looking for some opinions on repairing (likely replacing) the transom in my boat. I know I have rot in the wings around the hooks for a ski rope and around the motor mount area. I am likely looking at a full replacement. My main question is what is the least intrusion way to get the transom out and get a new one in there minimizing cutting to the exterior?

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[GT1000000]

Re: Transom Help Needed - 1975 Tri hull

Hi and welcome to the drydock on Iboats.

The link you posted to the phobucket pics only goes to their main page...

Best way to post pics is to click the IMG tag on the image you want to post, copy and paste into your reply here...

Once we get some good pics of what you have going on, we can help you out.

Have a good one,
GT1M

 

[Bob_VT]

Re: Transom Help Needed - 1975 Tri hull

First you need to read this in reference to your pictures http://forums.iboats.com/showthread.php?t=533219

There are a few methods available to you:

Remove the entire cap which it may come down to since you have not stated if all of your stringers are in good shape.

You could cut the cap off forward of the splashwell and only be working on the aft 5' or so of the boat.

You could do less cutting and use a pour capable transom material such as seacast or similar and there is a reference here http://forums.iboats.com/showthread.php?t=288451 item #7

You should really take some time and read all of the tips found there http://forums.iboats.com/showthread.php?t=288451 which will familiarize you with terms and methods of restoration.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

Thank you for the technical advice on posting.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

Here are the pics:



My goal is to mimimize the cosmetic damage/cut lines and provide for a durable repair/restoration. I have already replaced the deck and stringers about a year ago. My lack of knowledge led me to overlook the transom until recently I noticed a leak around the mounting bolt and probed only to find some really weak fiberglass and dark fluid exiting the rear lower mounting holes. I know water was getting in at the top trim/cap in the cutout area and around the mounts for the ski rope (really crunchy).

In some respects it seems easier to cutout inner glass (less outward cosmetic damage). I can get to the engine mount part of the transom via cap/trim removal. My concern is that I end up with a weak 3 piece transom.

Another thought (posted by Bob) is the cut the cap and drill out the rivets. If I cut it forward of the splash well I can get some plywood reinforcement to hold the pieces together as well to make it a stronger repair and give myself full access and the ability to install a one piece transom.

 

[Yacht Dr.]

Re: Transom Help Needed - 1975 Tri hull

The thing with them splashwell jobbies is that they are normally Bonded to the transom.

A real PITA to get undone depending on how they bonded it.

Cutting the cap forward of the transom still leaves you with that problem ( and now you have to finish your cuts on the sides of the cap ).

Its best if you can uncap totally. Sometimes just a few good whacks with a cold chisel or a small pry bar on the inside/underside bond point of the well will fracture whatever putty they put there. A few whacks with a deadblow hammer inside the well might help too.

Its a hit and miss kinda thing.

Sometimes its better to cut your well to trans on the inside of the well ( the finished side of the well ) to minimize damage to the well itself.

You would need to glass across the new transom to the sides and bottom of the well and then refinish it in this case.

One problem with the Pour-a-Trans materials is in your case the configuration of the transom. It would be almost impossible to get all of the transom core removed.

Or you might get lucky and there is no trans/well bond ..

Just gonna have to go one slow step at a time. Dont cut unless you have tried Everything.

Good luck.

YD.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

Thank you for your thoughts and expertise on this project. I am definitely moving slow and taking opinions and ideas so I can do this best possible way.

There is almost no adhesion with the top trim cap and glass in the motor cutout. I think has completely rotted away and the transom is distorted. I can push it back into place with my hand no problem. I think I will be able to get that area separated without to much trouble but I guess I will find out soon enough. By the way- the screws for the trim cap came out by hand. They weren't holding to any wood at all.

Right now I am building the motor stand and I will have that motor off in a few days. At that point I can remove the trim and see what I have there.

 

[Yacht Dr.]

Re: Transom Help Needed - 1975 Tri hull

By the way- the screws for the trim cap came out by hand. They weren't holding to any wood at all.

Yea.. dont you love it when then build a perfectly good transom seal and then blow a few dozen holes in it that can fail just for a good looking $5 piece of trim LOL .. oh god dont get me started .

Looking forward to your progress and pics .. we will be here.

YD.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

I get some pics up later but I am fairly certain there is some sort of bond between the well and the transom inner skin. The inner skin in many areas is deteriorated and crunchy. I will be reinforcing or replacing the inner skin after the new wood goes in. I am hoping I can gently detach the well and cap and then reglass it when I install it without damage.

One question I have is : Is there any way to piece a transom together and still make it strong. I am obviously looking for a shortcut and not have to remove the cap. I know I have to reglass the inner skin anyway. If I were to cut away the inner skin and remove all of the transom wood could I install a center and wing piece separately - maybe reinforce them with a steel plate that ties them together and then glass over that?

I am thinking that is not a good option but I am open to opinions. I know i can get to the top of the wings from under the cap so that is not an issue and I can get to the transom top where the motor mounts by removing the trim and glass cap at that location.

Shoot the idea down if you think it is not a good one.

 

[Yacht Dr.]

Re: Transom Help Needed - 1975 Tri hull

Uncap and do the transom in one piece ..

I strongly recommend that you dont scab the transom.

Sure you could use fiberglass to transfer the load across your hull..but its an undertaking if you want to do that.

This is not an I/O .. Your energy is NOT placed on your stringers .. its a full load across your trans/hull.

Two completely different methods of energy transfer.

Your trans is subject to the hullsides. Think electric .. path of least resistance ..

YD.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

Well this project is moving like molasses. This is what I have done so far:

1. Built a motor stand
2. Disconnected all linkages and lifted motor off the boat and placed on stand
3. Cut a small section of the cap and removed entire transom
4. Removed damaged and brittle fiberglass (inside) - outer shell is in good condition
5. Traced a template of the transom so I can cut new wood

Questions:

1. What type of wood should I use? I was thinking Treated Plywood but maybe a standard ply with epoxy sealer?
2. What adhesive should I use to bond the new plywood transom to the fiberglass shell
3. What type of adhesive should I use to bond the plywood to plywood (need to build it up to 1.25 inches)? I was thinking and epoxy adhesive - brand suggestions?

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

One more question:

1. The boat had a 1 1/8 transom prior. How do I know that it is sufficient? I can guess it made it for 30 plus years and that is a good indicator but I would like some metric or confirmation regarding thickness recommended and what if I do increase it what the benefits and drawbacks would be.

I am guessing that going to big would add weight and if there is no benefit why do it.

 

[Woodonglass]

Re: Transom Help Needed - 1975 Tri hull

Check the link in my signature below. It has the info you are looking for. Are you certain the Stringers in the boat are OK? Typically if the transom is bad, the stringers will have issues as well. Best to get it all done at the same time if needed.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

Thanks I will check out the link.. I did the stringers and floor already so I am good to go there.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull



Ok. So I cut the cap and I am in the process of cleaning the surfaces. I am going to get my template done and cut the plywood transom , epoxy seal everything and bond them together with an Epoxy Adhesive - probably the West system.

Question:

When I slide the transom into the pocket should I line the pocket with the adhesive filler to get a good bond or should I just coat the transom and slide it in. I am guessing a little of both is probably in order. Once I get a good bond with the outer shell and remaining glass pocket I am going to epoxy over the transom and tie it into the hull.

Anything else I should be aware of at this stage?

I am temporarily supporting the cap with some 2x4 scrap

 

[Yacht Dr.]

Re: Transom Help Needed - 1975 Tri hull

Its recommended that you completely remove the cap..then install the transom.

Sliding a transom into place is not normally done.

YD.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

Thank you for your response. Is that just for access? I can get to all areas very easily with the set up here. Not questioning the validity of your statement just trying to learn as much as I can about how to do this the best I can.

Thanks again.

 

[Yacht Dr.]

Re: Transom Help Needed - 1975 Tri hull

If you can clamp your transom with your current access without loosing any bonding material ( putty or whatever ) then your ok.

Just make sure your ok with it. Dry fit it and see how its going to install with your bonding material.

YD.

 

[sramos]

Re: Transom Help Needed - 1975 Tri hull

Thank you. I can get 2x4 's to clamp it. I was planning on coating it with epoxy adhesive, sliding it into place and then clamping it. Letting the outer shell bond cure first and then going in to glass the interior wall and reinforce it to the floor stringers and side of the hull. It it already pretty strong at the floor and the side of the hull just going to reinforce it to make sure I am good there too.

 

[Woodonglass]

Re: Transom Help Needed - 1975 Tri hull

Transom is typically glued to the outer shell using Thickened epoxy. Using Cabosil to thicken the resin to the consistency of creamy peanut butter and applying it to the shell and the wood and then clamping it in place. with the Splash well in place as it is, I don't know how you are planning on getting adequate clamping pressure on all areas of the transom and that is a critical procedure.