Repairing Hull - Deck Joint - RubRail Leaks

[Bacchus]

After using our MS 34 HT for a couple of seasons I finally found the source of periodic water in the bilge to be the hull - deck joint.
I repaired / resealed it last fall / this spring and happy to report the fix appears to be "permanent".
I summarized findings and fixes on our boat website and have posted a link over on the Yahoo MS forum.

I thought I'd also post it here so other Mainshipers (as well as other brands) might benefit from the learnings. I've had some comments re: which type of sealant / caulk is appropriate and whether to remove the rubrail at all or simply caulk the external joint as needed.
I don't wish to start a sealant caulk debate so I've suggested that anyone interested do some research and draw their own conclusions re: which caulk is best... although I have provided a few links that support my leaning

IMHO
1. - Removing the PVC / SS rubrail does provide the ability to fix the root cause of the leakage
2. - For those of us in freezing climes I'd rather NOT have trapped water anywhere it can freeze and create additional problems
3. - I don't want to escalate any debate regarding the +/- of silicone - I'd encourage folks to do their own investigation of the many / varied sources of info and draw their own conclusions.


The link to my summary is on our boat "Bacchus" website. (See "Bacchus" Projects Pg 4)
This includes diagrams, several links to other boaters experience and several resources / articles re: sealants and their selection.

I'd encourage any / all who are experiencing leakage to explore the summary & links and draw their own conclusion.
I'd also like to acknowledge and thank Steven Cyr - another Mainship owner - who has done a fantastic job of sharing his Mainship info on his Stella Blue website (link provided in my summary)

If others have experience, photos, etc of a similar hull - deck joint repair project I'd encourage them to share it here

 

[Symphony]

thanks for this post

 

[Sleeping Bear]

Hi Bacchus,

Am about to do this job on my 34 pilot. It is away from home, want to take everything I need, do you remember the size of the screws, and what length bolt and nut would be needed?

Thanks

 

[Bacchus]

Hi Bacchus,

Am about to do this job on my 34 pilot. It is away from home, want to take everything I need, do you remember the size of the screws, and what length bolt and nut would be needed?

Thanks

My memory not that good.
One thing I wish I had with me when I did mine was a 4" grinder to grind the screws / bolts used to reattach hull & deck off. The gap in the C shaped white vinyl piece is not overly large.
You may be able to make an educated guess from the pics on Steve Cyr's Stella Blue website. He did a good job of documenting the process. Wish I had seen this BEFORE tackling mine..

http://scyr.org/stellablue/index.php/upgrades/21-miscellaneous-fixes/46-hull-deck-joint

I would guess that the screws were #8s but just a guess. I had to use a size larger as the OEM had pulled through and wouldn't grip. That's why I'd prefer bolts & nuts but they would need to be longer to draw the parts together and then be cut flush w the nut.

 

[Sleeping Bear]

Just back from boat, will lay out what I saw/ did as I am sure most mainships have the same problem.

1) Did the joints with boat in the water from the floating dock, can't imagine doing it on the hard, too much up/ down the ladder.

2) port side was pretty open, the deck creaked when walked on, and in heavy going, all screws loose.

3) WHen taking the rub rail apart the stainless strip is held on to the rubber with half inch screws except for a few where longer screws go into the deck above the hull deck joint because the short screws interfered with the long screws holding the rubber on. Clear?

4) the rubber is held on with longer screws that go above the hull deck joint into the deck. This causes space above the hull deck joint (lip) for water and spider habitat.

5) The lips are held together with sheet metal screws and adhesive which fails.

6) took out the sheet metal screws, pulled out the old caulk, replaced, tightened up.

7) Installed 1/4 in flat head nuts and screws, 1 in is enough, counter sunk on bottom, nuts on top, no washers as there is no room. Cut screws with grinder, stepped on hot bit ouch stupid!!

8) installed rubber rail dry, new screws as a lot of the originals were broken, left 1/8 or so gap, filled with caulk, tightened up screws, removed xs caulk.

9) installed stainless strip.

10) All told about 10 hours a side, the rubber strip had to be persuaded into place with hammer, but it was 90 degrees out so that was not too bad.

 

[NIKBRUSH]

Mainship hull deck leak

Bacchus and Sleeping Bear,

Did you experience any shrinkage in the length of the rub rail when working on this project? Thanks.

Nick

 

[Bacchus]

Bacchus and Sleeping Bear,



Did you experience any shrinkage in the length of the rub rail when working on this project? Thanks.



Nick

My Mainship is differentnthan most with rubber insert. MS has a rigid plastic? "C" channel with a SS center insert that screws on so no rubber insert.

With rubber inserts shrinkage not uncommon. Either find / buy a new piece to fill gaps if large of some butyl caulk if small.

 

[NIKBRUSH]

Thanks Bacchus,

Starting the project tomorrow 4/30/23. I have 2007 MS Pilot 34, I suspect our rubrails are similar in configuration. Curious was your issue on both sides? Enjoy meeting you, when/if you pass thru Grosse Ile MI, on the Detroit River.
Nick

 

[Bacchus]

Thanks Bacchus,

Starting the project tomorrow 4/30/23. I have 2007 MS Pilot 34, I suspect our rubrails are similar in configuration. Curious was your issue on both sides? Enjoy meeting you, when/if you pass thru Grosse Ile MI, on the Detroit River.
Nick

Yes had some leaking spots on both port & stbd as well as stern.
Nothing apparent near bow. Once you remove the old problem areas will be more evident.

 

[NIKBRUSH]

Mainship hull deck leak

Some time has passed since I completed the hull deck repair on my 2007 MS Pilot 34. All is dry.

When it rained, a bit of water collected in the head sink cabinet. At first, I thought it was the 2 sink and bilge pump combiner. However, there was no evidence of a leak from the device. In August 2022, I started getting some water on the floor of the bedroom and kitchen. It was impossible to trace the leak due to the interior liner. I removed the port rub rail and found a gap about 2 feet long. The gap on the ends was about the thickness of a putty knife and less than 2 mm in the center. The gap surrounded the kitchen/bedroom bulkhead. I had six 10, 4200, Dap extreme stretch sealant and butyl tape. I chose to use butyl tape because the thickness of the crevice was small. When using butyl tape, water is your friend (it reduces the stickiness). You can stretch the tape like gum and fit it into a very small crevice. I pushed several layers of butyl tape (one behind the next) into the crevice with a wet putty knife. The tape went all the way back to the interior liner. Finally, I drilled several 1/4 inch holes in the bottom of the rub rail. All told, the task took about 8 hours.

It appears Mainship calked the top of the rub rail to the boat. The calk surrendered in some places and the rub rail acted as a gutter bringing the water to the bulkhead hull/deck crevice.

The configuration of the rub rail was identical to Bacchus. The rub rail did not shrink during the repair. The screws holding the stainless steel insert need a square drive. The square of the screw heads needed to be cleaned with an awl prior to removal. The 2 1/2 inch sheet metal screws holding the rub rail to the hull deck joint were troublesome. Many were bent or broke. I found spraying WD 40 into the hole before insertion of the new screw prevented the phillips head from stripping. In cases, where the head of the old screw had broken off I used a countersink on the rub rail and inserted a new screw next to the broken screw. All of the sheet metal screws connecting the hull to the deck were intact.

I purchased these products on Amazon:

The Hillman Group 823502 Stainless Steel Flat Head Phillips Sheet Metal Screw, 10-Inch x 2-1/2-Inch, 50-Pack, Brown

#8 x 1/2" Oval Head Sheet Metal Screws, Square Drive, Stainless Steel 18-8, Full Thread, Bright Finish, Self-Tapping, Type A, Quantity 100 by Fastener

Countersink Drill Bit Set, 5 Pieces High Speed Steel 82 Degree 5 Flute 6mm Round Shank Mill Cutter Bit Countersink in Sizes 1/4” 3/8” 1/2” 5/8” 3/4” Set with Carrying Case.

Good luck.

Nick

 

[Trawlerdream]

Excellent thread. Thanks for sharing.