2003 Mainship 390, Excessive Rain Exposes Leaks

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Veteran Member
Mar 13, 2020
United States
Vessel Name
Vessel Make
Mainship 390
With all of the rain we have had in VA it has exposed a couple of leaks on my 2003 390 Mainship.

One is a slight leak coming from my escape hatch over the v-berth. I have tried tightening the latch handles, we'll see but seems to help. Has anyone changed the gaskets on the three boat hatches? If yes, where to purchase and how difficult is it to change out?

The second leak is a drip coming down over the right side of the head sink and lands between the edge of the sink and the shower plexiglas. If you look up at the ceiling you see a space which is just below a pilot house glass window. Maybe the glass gaskets are leaking. I can see where some prior caulking has been done between the glass and the gasket. Has anyone changed the gaskets on the pilot house windows? If yes, where to purchase and how difficult is it to change out?
Same boat same leak

Hey there,

We had noticed a leak from the ceiling in the head sometime back but pouring rain here now. So started taking out the lower trim and the water is coming in at the lower right corner of the stbd forward facing window. I can see the seal is roughed up for several inches (not sure if the resin/varnish drips are related) and that area is wet with the water running into the corner. When I push on the glass I can see that the seal is broken and the water pump. Did you ever get yours fixed and if so how? Anyone else?

Thanks - Robert


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If the window is leaking then you will probably have to plull it out, clean the area and recaulk it. Caulking it while the window is still installed would be just a short term fix, if that.
Well Ugh

Does the window have a gasket? It doesn’t appear to, it looks like maybe the windows is attached & sealed with a black pliable mastic of some kind. I suspect that it’s not an easy job to remove that rather big window on my 2003 Mainship 390.

Thanks for the quick reply, Robert
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Don’t know exactly what you window is bedded with but if it is leaking then usually the only sure way is to pull the window and start over being scrupulously careful to get everything cleaned up and use a lot of whatever sealant you decide to use. On our last boat there were 4 useless windows that were aluminum framed and therefore straight. They were installed on a curved cabin side so of course they would leak. I pulled the windows and fiberglassed the openings closed. No more leaks. I added some 10x10 ventilation hatches to get the missing light and ventilation. The marina that we bought the boat out of told us they had been telling the PO for 15 years to do that because they had rebedded the windows 4 times and couldn’t stop the leaks.
Inspect the cabin hatch carefully to determine where the leak is.
Ours turned out to be at corner of the flange that mounted to the deck. I had some luck using metallic foil tape on the outside to seal in the area I thought was leaking to be sure that was it. Repair wasn't terribly difficult but required removal, clean up and replacement. I used Compass Marine Bed-It (butyl composition?) Tape and very pleased with results. He has good how to videos online.
Clean up of old caulk is critical, especially if someone used silicone. After extensive scraping I had to wire brush and sand w wet & dry paper after taping around the seal area to to avoid visible damage. I was amazed at how much silicone came off what looked like clean surface after scraping.

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