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Old 10-23-2020, 11:25 AM   #1
rgano
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City: Southport, FL near Panama City
Vessel Name: FROLIC
Vessel Model: Mainship 30 Pilot II since 2015. GB-42 1986-2015. Former Unlimited Tonnage Master
Join Date: Oct 2007
Posts: 4,984
30 Pilot II rub rail rebedding

I just finished rebedding the stbd rub rail and will be doing the port side when we get some cooler, drier weather in a week or so. Some observations of the notoriously leaky Mainship rub rail follow.

The deck mold-to-hull mold flange has a LOT of short stainless Phillips head screws! There must be one every 4 inches. Whether or not they contribute to the rain and salt spray water which finds its way into my bilge, I cannot say with any degree of certainty, BUT the sealant apparently squeezed out of the flange all along the joint would seem to indicate the nearby screws and flange itself are probably fairly well sealed.

What I can say for sure is that the thirty or so 2.5 inch long number 10 flathead Phillips drive screws holding the molded plastic rail to the hull were driven into the deck mold above the flange with NO sealant anywhere in the vicinity. At some point in the boat's life somebody had squeezed a tiny bit of silicone sealant into the narrow crease between the deck mold and the rubrail, and it was not completely continuous. This sealant was line was about the size of the lead in a number 2 wooden lead pencil - yes, tiny. Oddly, there is no such sealant on the port side.

I smeared a thin layer of sealant of the flange screws just to be thorough, and I laid a good sized bead of sealant just under the line of unsealed holes made by the rub rail screws before replacing the rail. Masking tape lines either side of the narrow gap between the top of the rail and the deck mold prevented the sealant from getting on the surfaces when the rail was replaced onto the flange causing the sealant to be squeezed upwards to form a bead which I then used my finger to remove. Thus all the rail screws were well sealed as they were replaced through the sealant.

This job was done with the boat hanging in the lift, and a couple of lessons were learned. As the stainless trim and the plastic mold were removed, cotton clothesline was used to suspend them from the handrail. It works out best to end up with the trim being suspended well above the joint and the plastic rub rail suspended below the flange to avoid dropping it on the big bead of sealant laid down before rail replacement. Also, the masking tape should be laid down before removing the rub rail to avoid guesswork later. It was a one-man job to remove the rail and clean up the area to ready it for rebedding, but it took two of us to get the aft section of the rail back in place and three people to get the longer forward portion into place.
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Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
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