390 Trawler 2000 swim platform fix

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suntansailor

Veteran Member
Joined
May 21, 2017
Messages
69
Location
Sint Maarten DWI
Vessel Name
Au Naturel
Vessel Make
2000 Mainship 390 Trawler
[FONT=&quot]Ever wonder what your 390 swim platform looks like inside?

Previous owner never followed up with MS warranty work on swim platform, so I tackled the job in the yard...not fun. My trawler was taking on water to the point that it listed to port significantly, as fellow boaters would say looks like you are sinking...no, not the case. Rain water would seep into the port section of the swim platform at the joint of platform to hull.

I took off the platform top, pulled all the wet foam out, re-glassed inside, installed equalizer tubes on inside compartment walls, installed a manual bilge pump just in can my glass work/seals did not work. I found that the edge of the swim platform top was off by 1/4 to 1/8", so factory just filled gap with white sealer which just failed in time. The swim platform "tub" was water proof as I filled with water and no leaks, so pretty sure the villain was the seal at the hull. By re-glassing that gap it fits tightly to hull, so no more leaks.
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[FONT=&quot]I then installed 3 large inspection hatches. Total task took a week plus 2 days waiting for things to dry. Now, no water in swim platform, and increased top speed by 1 knot due to weight reduction of wet foam and water in there. I will be curious on fuel consumption too with this fix.[/FONT]

[FONT=&quot]PS: I also installed SS grab rails on each side of the stern pull out boarding ladder, to make it easier to climb out of the water. But also designed them to assist on lifting dinghy out of water on davits as dinghy rub rail no longer gets caught on the swim platform rub rail. It now takes 5 minutes to bring dinghy up from water on davits. See last picture.
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5-6 years ago we had a leak in there from a rusted trim tab screw. We removed the tabs and glassed over the holes. Not sure where the waters coming from now, but I take a shop vac down every 6-10 months and vacuum out 30-50 gallons of water. Next haul we will pop the top, look for leak and probably install a bilge pump.
 
Nice job!


Did you install access ports before putting the top back on?


Our 2003 had the new design (no foam inside, and access covers installed at the factory.) We've never had a problem with it...
 
Yes, I installed 3 10" round flush hatches so I could see if any water is finding its way into the swim platform. I was in shock of how far off the swim platform top edge was not butted up against the curve of the transom. The factory stuffing lots of glue sealer to take up that gap was a joke (but apparently worked for many years as my trawler is 2000, so that means 17 years the sealer worked).



Now that top fits flush up to the hull, and 5200 makes it water tight. Installing the equalizer tubes between the walls of the sections inside the swim platform allows any water to migrate to the middle, where I installed a manual bilge pump (cartridge type) that can easily be replaced by reaching through the inspection hatch and detaching it from it's base.



The yard's quote was $5600+ to do the job, labor and materials. It was a real pain to do myself, but I wanted this to be rectified once and for all. Hopefully these pictures provide insight to others experiencing the same issue.
 
Thank You for posting this.
 

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