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Dave JZ · Swabby Joined: 18 Dec 2005 Posts: 264 Location: Wymore, NE

Ya Ya Ya Ya Ya I know what you'll all say.... where in the heck have you been..... well anyways It's not where I've been it's the fact I'm back again that matters...lol

We picked up a 1974 Tri-hull a few days weeks ago with a 1974 Chrysler 75hp motor. Motor runs like a dream and we've had it out on the lake about 3 times since we've had it (7 days) However I have noticed that the transom is getting weak so this winter or fall I'll prolly rip it apart to replace it.... You know... remove the top cap from the hull, take out all the rot and replace with new wood. Suprisingly the floor itself all over the boat is solid.. so I think the transom will be the only thing needing replaced. The bottom of the transom seams solid and dryas well. Just the top thats getting weak

Here's the catch. I looked everywhere on this thing and the top does not seperate from the hull. There is no seam under the rub rail. It is one solid piece(might have been fiberglassed together but that would mean a very good and clean seamon the underside) How in the heck should I go about replacing the transom. I should add that the transom does not cover the whole back of the boat. It follows the sides and then about 1/2 up it angles to the motor mount. It isn't the greatest pic but where the shape of the transom changes is the line the wood follows. Behind curved fiberglass is nothing. If anyone has any ideas on how to replace this transom please let me know but from the looks of things the top cap is not comming off. Thanks

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Dave JZ · Swabby Joined: 18 Dec 2005 Posts: 264 Location: Wymore, NE

A better look of it today and I found that it has definatly been glassed together. I can barely see the seam of the two. So any ideas?
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Calico · Posted: Sun May 17, 2009 7:56 pm Post subject:

On boats that don't come apart easily (like Hydrostreams) it is common to cut out the splashwell part of the top cap and replace the transom from the inside. You may be able to get the old transom out from the inside without removing the splashwell even but would need to put the new one in in pieces and you'd have to be careful where the joints are to keep the transom strong. You might ba able to get access to a lot of the transom just by removing the aluminum trim on top of it. There is always seacast as an option. It is axpensive but can save a lot of itching and cutting. You'd probably do the entire job through the top of the transom where the trim comes off in that case.
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Dave JZ · Swabby Joined: 18 Dec 2005 Posts: 264 Location: Wymore, NE

I checked into seacast but I wonder how difficult it would be to replace with the transom being the shape it is. I think I will have to cut the splashwell off and replace it that way. If I do it this way then I'll get a better look under the floor. The boat is still a very solid boat, and extremely light in my opinion. Floats well and planes within seconds after take-off so I don't believe that water has gotten under the floor and saturated foam. The floor is real solid all over. But at least if I cut out the rear 2' of the floor then I will know for sure whats there. I honestly believe that the drain for the splashwell is the reason the transom has gotten weak.
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Dave JZ · Swabby Joined: 18 Dec 2005 Posts: 264 Location: Wymore, NE

The more I think about it the more I think I will use sea cast to redo the transom. I want something that is going to last awhile. Cant see getting rid of the boat anytime soon, and if we got something different I would probably chop this one up to make it a fishing boat anyways. Has anyone seen it used or used sea cast????
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Wimperdink · Swabby Joined: 18 Dec 2005 Posts: 2328

I've not seen it at all... I'd love to hear your experience with it. You have a full sized job with this one methinks.
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Calico · Posted: Fri Jul 03, 2009 9:37 am Post subject:

I read about a project where a guy replaced the transom on a pretty big boat with Seacast. He used a long auger drill bit to chew out all of the old wood through the top of the transom between the skins and had everything scraped clean. It turned out really nice and was reportedly very strong. The stuff sets rock hard.
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Wimperdink · Swabby Joined: 18 Dec 2005 Posts: 2328

with seacast I've always thought about the likeness to cement and wondered how it doesn't crack without having some type of wire reinforcements in there . There's enough boats out there running it with bigger motors so I guess it works.
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Calico · Posted: Fri Jul 03, 2009 4:24 pm Post subject:

I believe Seacast has a lot of chopped glass and high density fillers in it.
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Wimperdink · Swabby Joined: 18 Dec 2005 Posts: 2328

so its like a solid block of fiberglass for the transom.... That makes better sense... While I know fiberglass is strong, a couple of 225's hanging off of it would worry me. I know we aren't talking near that hp, but.....
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Calico · Posted: Sat Jul 04, 2009 9:25 am Post subject:

That and the bond to the outer skins is where the strength comes from. If your transom is good on the outside but has a rotten core I think a Seacast transom would be a very strong core replacement.

That old Glastron I cut up had a rotten core and the motor had broken the outside skin across the bottom mounts and the inside skin across the tops. We're lucky we got it home with the motor still on it. That would have required a complete rebuild.

Higher horsepower boats would have knee braces and reinforced transoms. Some of them have steel framework embedded in the transome core. An easy reinforcement to make is to put on a couple of those aluminum plates that span the motor mounting bolts on the inside of the transom. The top one would do more good than the bottom which would help keep the bolts from pulling through if nothing else. A piece of angle aluminum would work also but not look so good.
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Dave JZ · Swabby Joined: 18 Dec 2005 Posts: 264 Location: Wymore, NE

From what I have read it is three part. The resin, hardner, and chopped glass. You mix the chopped glass with the resin. When you get it mixed, you add the hardner and mix until solid in color. Theres about 45 minute work time, and from what I have read you can mount your motor back on in as little as 24-48 hours. Last I checked it was 209 for 5 gallon worth of the mix... Not sure how much I will need since the transom is odd shaped. I figure by the time I Cut the splashwell off, replace with good quality wood, resin fiberglass etc etc and the replace the splashwell and refiberglass it back on, paint and finish I would be better off using sea cast. Then I would only have to glass the top "cap" that I removed to clean out and pour in the new.
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Calico · Posted: Sun Jul 05, 2009 11:36 am Post subject:

Yep!
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Dave JZ · Swabby Joined: 18 Dec 2005 Posts: 264 Location: Wymore, NE

So I'm bringing life back to the old post.... Had alot of fun out on the lake with this boat last summer and wanted to upgrade this spring... However like the pop-up my wife won't let me get rid of (due to the fact we have not used it...lol) It looks like I'll be fixing this transom this spring for a few more years with the boat. Still haven't gotten the garage cleaned out to put it in there but the weather is gettin warmer!!!!! I'm going to "dig" out the transom first.... see how it goes and go from there. I'll keep you posted.
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Dave JZ · Swabby Joined: 18 Dec 2005 Posts: 264 Location: Wymore, NE

It's getting warmer and yet I have not pulled the boat out yet. Was going to before the frost left the ground but that plan failed when I went out there to find under the carport the tire was in a low spot that happened to fill with water and then freeze. It was above the bottom of the rim..but not near as high as the axle. Just enough to keep the thing stuck. Now the frost is out off the ground and it's too muddy.. Hopefully this week or the beginning of next. Have a feeling my wife would rather me work on the camper.
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Wimperdink · Swabby Joined: 18 Dec 2005 Posts: 2328

gack don't work out in the cold... its miserable lol
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Dave JZ · Swabby Joined: 18 Dec 2005 Posts: 264 Location: Wymore, NE

I just wanted to get it moved
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