Structural Repair 23'

[abl1111]

Trying to repair the topside to liner joint near the helm ( just under the steering wheel ). It is a very structural part of the hull and I'm so very so very surprised at the OEM poor putty job used in this area.

Has anyone repaired this area ?

[abl1111]

The helm side below, has rotted core where the joint is and about 10-12" up. I have removed the bad core from the inside ( where the fuses are ) - be'atch of a job, tough access, and I am very surprised to find out that the only thing holding this joint together is potter putty - and that the putty was sandwiched between (2) gel coated parts ! And, the core material is, I believe ONLY 1/4" plywood ! That is thin for such a high stress area !

I am planning to glass the topside to the liner here, as I did on the passenger side.

Anyone done this ?

[abl1111]

Holy Cr*p. Talk about a void of info ! This is not the first time I've asked about this area. Tsunami and Scepter owners should know about this weak link in the lay-up of the boat.

When I finish, I'll post pix and the process. At least the next guy will have a baseline.

For now I'll just say - check the (6) bolts that hold the footrest in place - they go through core. And, remove the teak trim hiding the seam I have pictured above - a far from perfect bond was used there; Potter Putty sandwiched between (2) faces of gelcoat at a very high stress area equals a potential structural problem.

[Water Rat]

Ab,
I was hoping to get some pictures to include with my reply. I too am well aware of the importance of the structural aspect of this joint; its strength (or lack of) contributes greatly to eliminate twisting of the hull/deck structure in a seaway.

My solution was more mechanical. I had 1/4" aluminum plate fashioned by the same fabricator that did my hardtop/radar arch. The plate is approx. 4" wide, therefore about 2" om either side of the joint and follows the full length of the joint, both the vertical and horizontal, port and starboard.

It has worked very well over he last 10+ years. No pictures yet but you can catch a glimpse of it in a few pictures in the Gallery section; look under Chris Downey's 23' Sceptre. Feel free to ask any questions and good luck.

[abl1111]

Thanks for the reply. I thought of the mechanical approach but figured... what the hell, I haven't itched from grinding fiberglass in awhile, so I went that route...

I've documented the process, more for years down the road, to remind myself, " don't do this again ! ".

Here is where I am as of today:

Bad core



Removed Bad Core and Potter Putty seam



Aligned Seam before Epoxy



Epoxied Seam



Glassed in new core





NEXT... DuraGlass the core seams. Glass over the core and then use several layers of 1708 over the epoxied seams.

I'll send more pix.

I figured basic structural repair and then, because the main repair is hidden, I'll build it extra beefy... The repair area I need to learn a lot more about is color matching gelcoat - THAT IS TOUGH !

[kmoose]

From my experience with this issue I will give what insight I have. From dissecting a few of these I will tell you the seams are there and were not glassed for a reason and covered with trim. The Tsunami is a 3 part hull and there is a certain amount of "float" between the cap and deck. It is nessarsary as fiberglass boats must flex and joining these seams causes other complications. How do I know? Mine were glassed when the deck was raised and over a short amount of time the stress was transferred to other areas requiring much more additional glass work to rectify.
Potter putty was not some bad idea to take shortcuts but a material used to close gaps and provide support between the three hull components ( hull, deck/liner, and cap) with one of the functions being to allow tolerance for movement due to hull flex.

To me the issue seems to be with the core material which you are fixing. My recommendation is to not connect the deck and cap in anyway unless you want to do more extensive glass work that will render a less than factory look. Matching gel coat will be the least of your issues.

[abl1111]

What other areas were affected in your experience ?

Correct me if I'm wrong ( I don't mean in that in an wise-a** way ) - aren't most hulls made in 3 parts; hull, liner and topside ? I can't fathom that the potter putty was put there as a spacer. At one point, the putty was fastened to each side of the joint.

The core that was rotted was 1/4" thick - even when new, it would not have been enough to hold it right.

I agree about a hull needing to flex a bit, but these area(s) - on either side of the companion-way, I believe, warrant rigidity - or the teak door would get pummeled ( which I've heard is a common issue with these hulls )...

My thought was that it was just a way to keep manufacturing costs less and easier - otherwise, there would have to be a decent amount of add'l glassing, fairing and gelcoating.

As I am a novice, I take all input. Thoughts ?

[kmoose]

Yes, all manufacturers use some form of "putty" to join/nest caps to liners and decks to stringers on the main hull. The areas that stress was transferred in my case were at the door jams entering the cabin at the liner supports struts at the deck level causing cracks that ended up causing water to enter the deck coring. If you tie it all together the system will find the weakest areas to shear and delaminate the glass at those points to relieve the stress due to flex.

Can it be done in a way to tie everything together and stop this? Sure, mine is in the process of getting it done but it requires a full disassembly of the cap and deck. Additional bulkheads tied to the hull, deck and stringers have to be glassed as well as the cap and hull at the rub rail have to be glassed solid. This is just a short list and is no guaranty that at some point long term stress won't emerge at a tie point. We are not just talking about minor glass work as it is running us close to $10k getting it done right by a pro.

Again, Potter didn't leave those unjoined seams by accident. They are part of a proven system that has held these boats together in one piece for decades without hull failures. The coring issue you have is not uncommon at that location but it has nothing to do with putty or the untied cap joints. It's the same issue that plagues most all wood cored panels and decks at some point. It's caused by ingress of moisture usually brought about through the helm holes and switches installed on the face of the helm station in this particular instance.

[McGillicuddy]

I concur with Kmoose, ample torsional strength is provided by the cap and cockpit insert. The cuddy cap is stout enough to walk on. Plenty of lateral shear strength, I think. Also you have those vertical pillars (your vertical seam)inside the gunnels adding rigidity.

The bulkhead is effectively is a minimal load-bearing wall creating a separate cabin. The turn in toward the door also adds stability.

On the Seafari, the bulkhead is connected to the cockpit insert w/ 4 screws on each side and to the dash with 4 or 5 more no glass or epoxy on either of the joints. The 21 has no bulkhead and you can still walk on the fore deck. The Seavette has 2 sets of bulkheads and I don't remember that either of them were glassed to anything, just some dabs of 5200 or potter putty, and maybe some after market lifecaulk or same.

[cdavisdb]

To add to Kmoose: Flex in a boat is tricky. My Seafari 25 had a structural problem probably caused by Potter removing some things Moesly designed into the boat. Its showed up in several 25s. Mine was made much worse by some rotten bulkheads. I fixed it, being very careful not to create hard points. Did not quite succeed. Sure enough, the hull found different areas to flex and after a few years I started seeing hair line cracks in the gelcoat. Fixed that this year, hopefully before it got serious. Give it a couple of years and I'll know if the flex just transferred somewhere else or maybe i really fixed it.