Which sealant for splashwell seams on '87 18' SuperSport?

[olympic]

My '87 18' SS has caulk/sealant of some type where the splashwell joins to the transom (the vertical side seams). The caulk appears to be a bit older but mostly intact. There is a small crack showing from the splashwell base on one side up about 3 inches after which there is existing caulk of some sort. I need to get that crack filled.

I was wondering which is the best sealant for the job. Would 3M 5200 fast cure be a good choice? If so, should I try to remove all existing caulk up that entire seam or will 5200 work okay over existing? If so should I clean existing with mineral spirits first? I don't know what the "existing" sealant is. It looks like some of the other splashwell joints appears to have a very light bead of caulk as well, but those appear to be perhaps original and in good shape. The sides where the splashwell joins to the transom is where the issue is and it appears to have been done by PO at some point.

Thanks in advance for any guidance.

 

[dozerII]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

3M 4200 would be the better choice as it is not as permanent as 5200. Make sure to check your transom over real well if the caulk is cracked it may be on the way out. If it checks out good then clean as much loose old caulk out as possible, then put a bead of the new in.
When I install the splash well after a new transom I use glazers tape as the main seal then either 4200 or Sikaflex for the finish bead.

 

[jbcurt00]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

Refresh my memory, but this SS isn't getting much, if any rehab work?

Gaps in the caulking, cracks in the splashwell, and previous added caulking by a previous owner all suggest that you should thoroughly check the plywood transom before re-sealing any cracks or gaps.

Don't let good wood showing on the face of the plywood fool you. Lots of transoms that appear good to go, aren't....

If all is well, yep, Dozer has ya covered, 3M 4200/5200 or the products he suggested will work.

 

[olympic]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

I will read up on checking out the transom as I know there is a ton of info here on the forums. Would love to get a season out of it before having to do the transom.....ideally want to know what other issues there are with the boat. Was hoping to use it more or less as is for at least a season before taking on the major restoration. Want to make sure the boat really works for us.

Sounds like 4200 is the way to go here IF it checks out well enough for at least a season.

Can I check flex by sitting up on front iof splashwell and putting feet against transom and push against it? If so is any movement at all mean its bad?

Also, was thinking of adding a trolling motor bracket to starboard side in the back - will drilling that work okay for core sample to help gauge its condition for at least a season?

I do plan to pull kids on tube occasionally so want to be sure its strong enough to hold up.

 

[astor]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

This is what the gaps in my splash well looked like on my 87 18' SuperSport.

and this was my transom

hopefully your's isn't as bad as mine was.

 

[classiccat]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

I do plan to pull kids on tube occasionally so want to be sure its strong enough to hold up.

See post #2 of BillaVista's V5 Holiday Resto.

 

[olympic]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

You guys are scaring me a bit. I wasn't planning to start my own restoration thread just yet.

Astor, I'd say your gap is at least similar....can't fully tell because of the caulk in place on mine. See attached pics. I did push back on the transom with my feet from the splashwell side of the boat and stood and bounced lightly on the motor cav plate and couldn't get flex from what I could see.

BlueFin, that's an eye opening post/thread there you referenced. I see the transom was bad on that boat...but was that also caused by the placement of the eye that was used for tubing? I have a pic of where mine is located on the side I was able to easily get to. Not sure how that will work with the swim step but given there was a waterski rope included I assume they used the hooks on either side.

Thanks again to everyone for the continued advice and Happy Holidays!

 

[dozerII]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

By looking at the pictures above it may be worse than you think. Some one has added a piece of aluminum over the transom cap. If there is flex in the transom the cap cracks on either side of the motor. This may be old damage, is the plywood on the transom under the splashwell painted or sealed in any way? If it is then then it has been replaced and some one just put the aluminum piece over the cap to make it look better, if the wood is raw with no coatings there is a good chance it is original.

 

[olympic]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

By looking at the pictures above it may be worse than you think. Some one has added a piece of aluminum over the transom cap. If there is flex in the transom the cap cracks on either side of the motor. This may be old damage, is the plywood on the transom under the splashwell painted or sealed in any way? If it is then then it has been replaced and some one just put the aluminum piece over the cap to make it look better, if the wood is raw with no coatings there is a good chance it is original.

The aluminum cap looks factory the way it's been done, so if it's not then it was done nicely. Did they not have aluminum caps back in '87? Looking under the splashwell at the transom the wood is not sealed in any way so I assume it's original.

 

[classiccat]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

excerpt from my SS's introductory post:

...
Cosmetically the boat leaves little to be desired yet once the motor is serviced and electrical is brought up-to-speed, the rig is fully functional. With some long overdue TLC on this engine, I may delay the resto for a season-or-2...what do you think? ...

:facepalm:

:lol:

 

[dozerII]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

The piece I'm referring to is over top of the side pieces, but you are right it does look like it's been there since new.

 

[olympic]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

Is it too late to change my Santa list?

 

[jbcurt00]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

Nope, not too late......

As is often the case, the easily accessed & probed areas of the transom aren't wholly accurate in testing the soundness of the plywood.

Or a speedo/transducer mount that's screwed onto the transom rather then thru bolted to it? Any thru bolts you can remove & probe the interior surfaces of a thru hole in the plywood?

The good news is a transom replacement on a tinny doesn't have to be a fully involved resto..... May not even need to remove any of the deck.....

 

[olympic]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

Nope, not too late......

As is often the case, the easily accessed & probed areas of the transom aren't wholly accurate in testing the soundness of the plywood.

Or a speedo/transducer mount that's screwed onto the transom rather then thru bolted to it? Any thru bolts you can remove & probe the interior surfaces of a thru hole in the plywood?

The good news is a transom replacement on a tinny doesn't have to be a fully involved resto..... May not even need to remove any of the deck.....

PO had recently (early summer) put a fish finder transducer that is screwed into the transom. Would I be able to discern anything by backing those out?

I was planning to bolt up a kicker motor bracket to the transom - that would work for core samples, yes? I haven't purchased the bracket yet so not quite ready to go drill holes but will be ready to do so in near future.

 

[jbcurt00]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

Perhaps taking the transducer loose would give you a small window into the side of the transom that faces the hull.

If water leaks out of that now empty hole when you pull a screw, then yep it's time to replace the transom :facepalm:

Tinny transom plywood doesn't typically extend down to the bottom of the transom aluminum skin, most often it doesn't. Before you pull those mounting screws, confirm they're into the plywood.

You can also pull 1 motor mount thru bolt at a time & get a better (larger) hole to probe.

You may find another thru bolt below the splashwell.

The one on the left is probably a motor mount bolt. What's the other one? Swim platform?

It'd be a good one to pull too.

ALL those thru bolts should be well sealed on the exterior aluminum skin, the thru holes should be sealed, and if IN the splashwell (like the 2 I re-posted) on the interior side.

 

[olympic]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

The one on the left is probably a motor mount bolt. What's the other one? Swim platform?

The left one is just a through the transom/hull bolt and is not a motor mount bolt. There is a matching one on the other side and both have factory paint it appears. That right side bolt is a swim platform bolt. I'll pull that swim one and replace with stainless and seal it so I'll see what that reveals. Will probably be a couple/few days as a bit tied up with the holidays.

 

[astor]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

The aluminum cap looks factory the way it's been done, so if it's not then it was done nicely. Did they not have aluminum caps back in '87? Looking under the splashwell at the transom the wood is not sealed in any way so I assume it's original.

I agree, it looks factory, the same as my 87 18' SS. there are three pieces to the transom cap. a left and right pieces that curl up and go vertical, and the part of the splashwell that wraps over the horizontal. My transom was so rotted that the two vertical pieces were broken under the splash well, I just had them welded. The welds are where these two pieces went under the splash well.

 

[olympic]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

Astor - I hope mine aren't cracked.

Anyone know if the areas to either side of the splashwell are filled with foam or not? Just wondering if I was to try and access that area if I'd be able to get a better look at the transom. Wouldn't take much to remove the screws off the covers and look...was just curious if I am going to remove it just to see a huge block of foam.

 

[astor]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

Olympic, those two side areas are filled with loose blocks of white styrofoam, when you remove the two front panels they can be easily removed. see the pictures in post #10 of my rebuild thread.

http://forums.iboats.com/starcraft-boats/87-ss180-first-rebuild-568083.html#post3906591

 

[olympic]

Re: Which sealant for splashwell seams on '87 18' SuperSport?

Olympic, those two side areas are filled with loose blocks of white styrofoam, when you remove the two front panels they can be easily removed. see the pictures in post #10 of my rebuild thread.

Thanks Astor. I had checked out your thread and wondered if that's where those blocks came from. Thanks for the confirmation. Will be removing the panels later this week to see how things look back there.