Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

[Woodonglass]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

This might be of interest...
"Fabricating Decks, Stringers, and Transoms"

 

[JASinIL2006]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

This might be of interest...
"Fabricating Decks, Stringers, and Transoms"

"Might" be of interest? Man, I've memorized that thing. It's like it's tattooed on the inside of my eyelids!

Jim

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Jim, not cool man. I hope that I do this right the first time. This is one of my many projects right now.

Woodonglass, I looked through your post before and have planned to follow it to the t. As suggested, I will also be drilling three 1/2" holes to let the PB ooze out. This was done on the factory transom.

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Hey gents, I'm also wondering if I should do something to help any water from ponding just below the transom. See below pic.



I believe that most of the rot was caused by the ladder leaking. But I suppose water ponding in this area could have contributed. Should or could I just build up this area with PB and slope it to drain? Any other ideas.

Woodonglass, in this picture you can see one of the three "bleeder" holes on the transom.

 

[Friscoboater]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Friscoboater, Larson originally only tabbed the very top of the transom to the hull. BTW, thanks so much for going through all the extra trouble of posting all the awesome pictures and videos. Between you and all the other great people on this forum, I would probably be looking a boat with a blown motor and taking a huge loss on this boat. Back to the transom, are you suggesting that instead of going with the original transom design to follow the contour of the fiberglass so that I could tab around the center portion? Or staying with the original design, but removing the foam so you can reach behind the plywood to tab?

I confirmed today that I can get marine fiberglass supplies locally. But, their expensive on the resin; $4 per pound and I was told it weighs 10 lbs per gallon so $10 more per gallon than US Composites. I?d love to business locally, but that?s a little steep. Another item, when I asked about milled fibers they said they use purlay (sp?). He compared it to the white foamy substance you add to potting soil. Sounds fishy to me. Can anyone educate me?

Yes sir, I would remove the foam and tab to the hull. Sorry for the late reply.

 

[GT1000000]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Hey gents, I'm also wondering if I should do something to help any water from ponding just below the transom. See below pic.

View attachment 184026

I believe that most of the rot was caused by the ladder leaking. But I suppose water ponding in this area could have contributed. Should or could I just build up this area with PB and slope it to drain? Any other ideas.

Woodonglass, in this picture you can see one of the three "bleeder" holes on the transom.

That is basically what I did with mine...I tried to make the bilge drain the lowest spot in the bilge...

Since this pic was taken, I have since made the opening a little larger, inserted a PVC liner and shaped it with a rotary tool so that there is absolutely no lip...
You can do it with a combination of PB, mat/cloth, or even a shaped piece of wood glassed in...
Another method you could use if you leave it the same, is to use a cotton rope or a strip of cotton, inserted in the bilge drain from the outside, when you return from a day of boating and it acts like a wick to help evacuate any remaining water...

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

GT1 thanks for the info.

I have one more thought before I install this transom and would like to run it by you guys. The reason I starting questioning the transom was due to some exterior cracking below the outdrive. See below pic.


Upon grinding on the interior side I see the hair line cracks. Additionally after removing the outdrive, the gimbal plate had pushed the two bottom corners into the hull which cracked and moved a small portion of the hull in approximately 1/16 of inch. I realize that I will need to do some work to the exterior side of the hull when I'm completed on the inside of the boat. However, should I consider adding at least one layer of 1708 to the interior side before placing the new transom to help reinforce this area?

 

[JASinIL2006]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Do you see cracks in the fiberglass from inside the boat (i.e., where you've ground away cleaning out the old transom)?

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Yes, I can see the cracks on the inside. They are very small, but noticable. Also, unlike the uniform profile in the upper part of the hull the bottom side is pretty distressed, eg air pockets, lamination all in all does not appear very sound.

 

[rickryder]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

They sure do slap them together at the factory...... You'll make it better than new

You can add a layer of csm to the hull at the transom or biax if you like....just watch your overall thickness.

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot



The new transom ready for trimming and key hole cutout. Getting itchy to start putting things back together!

 

[JASinIL2006]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Yes, I can see the cracks on the inside. They are very small, but noticable. Also, unlike the uniform profile in the upper part of the hull the bottom side is pretty distressed, eg air pockets, lamination all in all does not appear very sound.

I am sure the experts will weigh in, but if there are cracks running through the hull, I absolutely would want to put some 1708 there. I'd want to make sure that area was very strong and that no water can infiltrate along the cracks from the outside. I assume you'll fix the gel coat on the outside after the interior part is done, yes?

Jim

EDIT: The transom looks great!

 

[Woodonglass]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

I would do some extra grinding in that area in order to lay some CSM and 1708 back in there but keep the thickness the same. Do this on the inside and the outside and she'll be good as new. Maybe better.

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Okay, thank you gents. I will try and post some pics tonight so you guys can see what I'm dealing with. But, I really like the idea of grinding most of out and putting a layer of 1708 on both sides to make sure that this distressed area is repaired well.

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Well gents, I have have not been able to get a good picture of the cracking below the outdrive but hope to tomorrow when I will have some good light.

However, last night I got my fiberglass supplies in and I felt like a kid on Christmas morning. So I had to mix up some PB and fill in my screw holes on the new transom. I'm currently working in the garage with some electric heaters. Of course I was wearing my mask and when I finished up I took off my mask and was overcome with the fumes. I then got a case of cold sweat because my garage also has my gas water heater in it. Should I be concerned with any potential of ignition of the fumes?

 

[JASinIL2006]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Congrats on getting your stuff. I know just what you mean!

I've been doing all my glassing in a garage with propane heaters running. I recall reading in another thread here that the amount of resin we're using won't give off enough volatiles to cause problems. I'd be a bit more comfortable with a heater running continuously than one that kicks on occasionally, though. Seems like the continuously running heater wouldn't allow volatiles to build up. Does your gas water heater have a pilot light? If so, there was flame present the whole time anyway... I was bit apprehensive the first couple times I glassed with the heater running, but I don't worry about it now.

Jim

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Tried to knock out as much as I could today. I was hoping that I would be able to get the new transom in this weekend. However, due to the weather tomorrow it doesn't look like that is going to happen. Here is what I got checked off. Glassed the new transom, laid in a layer of 1708 on the bottom of the hull to reinforce the old cracked area (thinking about doing another layer) and got all the foam removed from the void area behind the transom. Here are some pictures...

The darker lines are the large cracks where the lower part of the outdrive was pushing through the hull



A look from the exterior



Its now a engine/outdrive/fiberglass roll dolly. The garage is a wreck! But got the transom wrapped in glass.



All foam from transom area is gone, well most of it anyway.



I also had a little extra time to play with the carpet glue. That stuff is really getting to me. I bought some professional adhesive removal and left it on for 30 minutes and yet that stuff was still like concrete. Lucky the store manager told me if it didn't work then they would give me my $ back. Other than this I've tried MEK though it was the "substitute" kind and goo gone. I don't like using the grinder cause I end up taking off more fiberglass than glue, and the wire wheel just doesn't cut it. Guess ill try another chemical...

 

[JASinIL2006]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

I never found anything that removed the dried glue. The MEK substitute didn't touch it. Someone recommended carb cleaner, but it didn't do anything either. I ended up gently grinding it off...

Your transom shield looks nice. I see what you mean about those cracks in the hull. I'd probably put at least another layer of 1708 on it if it were mine. It'll be supported better by your new transom so it shouldn't flex, but still...

Good luck with the chemical search. I'd be interested to hear if you ever find anything.

Jim

 

[HalfFish5087]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Transom installed!!! I must admit I thought I would use much less PB. I saw frisco's post of 3 qrts and thought I would use the same. Well that was way off as I mixed up 12 qrts and used close to 11 qrts. All in all, I mixed it up slow enough that I had close to 40 min before it started to kick. Based on some crude measurements I think I'm within a 16th of an inch. We'll see for sure tomorrow. Also, yesterday I put on another layer of 1708 on my distressed area at the bottom of hull.





Tomorrow I hope to tab in the transom and maybe get the stringers re-installed.

 

[ezmobee]

Re: Is it worth it? '98 Larson 5.7GS DP Lower Transom Rot

Nice work.