1967 18' Larson All-American 186

[Nabstar]

Initially when I bought the boat, I field tested the strength of the transom by flexing the outboard. There was slight flex but about the amount you'd expect from plywood but not enough to be scared and the floor felt rather solid .... so I proceeded without replacing those items. What I've noticed however, is that the overboard drain hole in the splashwell has some cracks around it even after painting and seems to be adding small stress cracks which is what alerted me to begin with ..... that flex was becoming an issue. And all those little cracks have probably introduced water into the transom wood. During the resto I drilled holes at the base of the transom for underwater lights. The wood that came off the drill bit was dry but that may have changed now from water above.

All in all, I want to correct the problem in the proper manner, whatever that may be, but want to attempt to disturb the rest of the boat as little as possible since it's already "finished" & the exterior paint is beautiful.

 

[kcassells]

That's going to be a hard trick to pull off. Once you're in it you're in it. Some people have and do put alot of faith in seacaste and it does work in alot of situations. Your primary goal should be to be able to determine the status of the transom {we know is failing}, stringers, bulkheads etc. of the rest of the boat. You did not tell us what size
"core drillings " you did.
Perhaps since your thinking seacaste cut an entire chunk out of the transom from the rear and make a real good visual/reachable area to get at the stringers/bulkheads in the rear to make determinations/tests. You can always replace the entire transom skin. On a note this approach though trying to save the aesthetics may still not work due to what other structures prevent you from getting good access. Like cutting up the floor Ouch!!
Just hate cutting into the pretty boat now but ..prove me wrong.

 

[coolbri70]

thats a good looking boat worthy of repair, if you go with plywood make sure it is sealed well. i replaced the transom in mine with plywood, but the drain tube did'nt seal and the wood got wet and is back to flexing:doh: so this spring i am putting seacast in it, guess i will have more pics for my resto tread

 

[kcassells]

thats a good looking boat worthy of repair, if you go with plywood make sure it is sealed well. i replaced the transom in mine with plywood, but the drain tube did'nt seal and the wood got wet and is back to flexing:doh: so this spring i am putting seacast in it, guess i will have more pics for my resto tread

Oufa! Sorry to hear that Coolbri! Sure is a pretty boat.

 

[Tnstratofam]

You could pop the cap, but as kc suggested there is probably more damage lying in wait under the deck. The first step I would imagine would be to take some core samples of the transom from the bottom up on the inside as suggested. That will at least tell you where the rot is located. Top, middle, bottom, or all.

 

[sphelps]

If you do seacast ALL of the transom wood will have to come out ... And get the inside of the skin as clean as you can possibly get it .. You can do this without cutting into the outside of the transom . But can you be sure that the stringers aren't gone also ?

 

[Nabstar]

Well, it's become clear to me that I misquoted my friend/restoration specialist. If you have interest, here's his correction of my initial assertion.

I finally accessed the I-boats forum link you sent me. I now understand the negative responses you received and your apprehension to move forward with the transom repairs. I was misquoted on a number of issues in the 2/16/15 #35 segment, which I would like to clarify.

1. You said I wanted to ?place a 3/8? piece of aluminum angle atop the transom and that?s it for the transom repairs? That is not what I said. With the exception of the thickness of the aluminum angle I recommended there was no definition on the overall length, depth, design, or method of installation of this critical part.
2. The corrective measures re: repairing the wood substrate in the transom and insuring the structural integrity of said part that I went into a great deal of detail, was completely omitted in the same segment as above.
3. Regarding the splash well reinforcement procedure, KCASELLS commented he ?didn?t think that the splash well was designed to take the kind of weight/force displacement.? ?House of cards? he said. I couldn?t agree more. But, again, that is not what I said. I specifically focused on the U-channel crossbeam in front of the splash well, big difference.

In addition to that there was no definition regarding the actual materials, design, fabrication or installation process I described to you in this area. You simply said I wanted to glass a couple layers of plywood against the front of the splash well, bolt up some allthread (also undefined) and that?s it!

Let me re-iterate what I actually proposed in this area. My plan was to use Baltic Birch multi ply plywood as that product possess approximately 35% more rigidity and tensile strength than that of any form of marine plywood of the same thickness; In this case ?? per lamination. The first part was to span the entire length of the U-beam aft section all the way to the port and starboard corners. This part would be bonded directly to the existing fiberglass molded part with mat, biaxial and triaxial fiberglass sandwiched in between the ply and boat. Then an additional glass bond of the same format would be applied to the outer section of the first ply transcending around the corners and continuing 90 degree aft about 10? which would spread any loads across the entire beam and into the fore and aft vertical sides of the splash well.

Then an additional section of ?? x 36? Baltic would be laminated to part #1 in the same manner and the whole structure glassed over. All resin would be of the epoxy West System #105 variety as this product also possesses over 35% greater strength to weight ratios as compared to polyester which your boat was made of originally. So, let?s review: A. ?? of original fiberglass already in place, B. (3) epoxy/fiberglass laminations 1/8?, C. (2) ?? panels of BB ply for a total thickness of 2-1/8? which is 3/8? thicker than your transom. In addition the grater thickness factor and the greater strength of the materials used, one would have to conclude the reinforced cross beam would be far stronger per square inch if compared to the transom and fully capable of becoming a load bearing structure.

No wonder the forum gurus think I?m some kind of inexperienced, clueless Bozo!

Back to the transom wood issues; I reviewed the Sea Cast product information; pretty neat stuff. If your transom were compromised to the levels I reviewed with this product I would fully support the use of this product. However, after sounding your transom it became clear to me, and others, it?s in way too good of shape to require such an invasive procedure. It was reassuring to see this product infuses fibrous materials in the powder catalyst, which supports my theory of maintaining this property for structural integrity as opposed to just filling a cavity with resin.

For the record, what I proposed was to drill down vertically 12-16? from the top cap of the transom, ?? diameter core sample holes at approximately 2? on center intervals and carefully inspecting the samples as they emit from the drill. At the end of this phase we will have far more accurate data as to the integrity. I suspect the conclusions will be consistent with the sounding data we?ve already attained.

The by product of this procedure is we now have a row of deep cavities to inject penetrating epoxy reduced 15% with denatured alcohol, which will enhance the saturation process, then evaporate and leave behind a fully cured plasticized fiber rich, rot proof, structurally sound substrate; a classic boat owner?s dream! At this point I would implement the remaining aspects of the job, which I believe we discussed in detail, both verbally and now in draft and it?s a done deal?go play!

In closing, please feel free to post any portion of this e mail on the aforementioned forum providing it?s my version of what I said.

Let the critics commence!

 

[kcassells]

No Critics here..We all just try to put the persons on a good build rather than trouble later or even injury.
Thank you for the clarification. A lot different than what was stated prior.
The only thing I would change is the bold font . lol!
Looking forward to a detailed picture/renovation!

 

[jbcurt00]

I read that several times and frankly cant make sense of the 'plan' execpt that he wants to drill 12-16" deep 1/4" holes into the edge of the transom ply ever 2"?? That in and if itself will compromise the transom, IMO.

Best of luck w your project.

 

[64osby]

The original transom lasted over 40 years.

The rework proposed sounds like it is trying to make up for a design defect that doesn't exist.

I say rebuild the transom per the original build or try the Seacast. When the transom is out you might be able to see if there is additional work to be performed on the stringers.

 

[Woodonglass]

Uhmm, I hate to say I told you so...but I told you so. Post #2 Oct 23, 2011, I asked the Transom Flex question. Any flex is a No No. Newb's take notice!!!

nabstar, IMHO, but shared by others, since your craft is such a beautiful boat, the only method to ensure the transom is restored properly is to do a full replacement. I'd De-capitate her and do it correctly. Personally I see no reason to use Seacast. A properly installed Wood core transom will last 50+ years. That's good enuf for me!!! If you're diligent you can do this in a month of weekend work IF you don't discover more issues during the restoration.

Again just my 2 cents!!!

 

[kcassells]

This is sounding a lot more like future litigation procedures for the Nabstar prior to work being performed. Under the circumstances as a forum and as a marine owner/shop {who he has called a friend} I'd say it's time to walk away from dealing with the issues and let Nabstar sort it out himself. There is obviously more to the problems that we aren't aware of and he threw his friend under the bus.
Been there done that, got the tail end of it too many times from people like that.
Good luck with the rehab.

 

[hadaveha]

Wow iboats has become stressful, sorry about the transom, you will get it squared away and man she is beutifull

 

[Nabstar]

I think you're reading into it too much kcassells. No one is throwing anyone under the bus. My friend/restoration guru is an amazing guy. He's got my back and only wants the best for my boat & myself. I tried to take the method he suggested for reparations & let you guys give me your opinions. Most responses on iboats come from people with much greater knowledge than myself ..... for which I'm grateful to have access to. Unfortunately I didn't explain his proposed method well enough ..... I guess that'll happen when you're just a "cadet".

As I'm sure you can see, I've wanted to take an old beater and make it into something beautiful so it shouldn't be a surprise that I want to make an informed decision (prior to spending more time & money) regarding a really important part of the boat. I truly appreciate every ounce of feedback whether it be positive or negative.

 

[kcassells]

Cadet Nab,
Yup..... Nothing to say. I'll just be a Gentleman in regards to your build and comments.
Good luck with the build and look forward to sharing info on the project you have going on.

 

[Woodonglass]

Nabstar, I forgot to mention that I disagree with your Boating Guru friend and his CPES Drilling scenario. CPES is NOT a good product. Using solvents to thin epoxy is a BAD idea and a CHEAP TRICK as far as I'm concerned and proven to weaken the overall properties of the epoxy. Your boat is much to nice to do anything but totaly replace the transom the correct and proper way.

 

[Nabstar]

Thank you for the feedback. I'll take all the help and guidance I can get.

 

[Nabstar]

And WoodOnGlass, I do remember when you mentioned to me, way back when, about checking for transom flex before getting too far along. Back then, when I grabbed the engine and gave some hefty tugs, it was remarkably stiff so I thought I might be one of the lucky ones. After painting the boat & using it for about a year and a half I noticed that the overboard drain hole (in the center of the splashwell just below the outboard) had some chipped paint & some minor cracks. I also noticed that when the splashwell had some water in it that it would drip (from that drain hole) straight down into the bilge. One problem could be that those cracks have allowed water into the transom wood turning a "pretty good" piece of wood into something "pretty bad". Essentially, weakening the center of the transom.

 

[Woodonglass]

Possibly but 4 years with the care I presume you've given her would not have caused this to have occurred. Its an accumulation of many years to cause the wood to decay to this point. It really is disappointing I'm sure to have to come to the realization that the transom has to be replaced but I see no other course of action. By the way, this just came up on my local craigslist. http://tulsa.craigslist.org/boa/4884638989.html I might go take a look this weekend!!! I really like your boat and this one could be a candidate for my next project.

 

[Nabstar]

That Larson looks good. I've always been a fan of them having grown up in MInnesota. It wouldn't surprise me if there's one on each of the 10,000 lakes.