carpet soaked in guest berth on 2003 Mainship 390

I have a Mainship berthed in Cordova Alaska - lots of rain. Got to the boat this week and the guest berth carpet is soaked. Main berth has wet floor too (base floor) but not as bad. I obviously have either a leak in the bow and the rain is getting in. no visible sign of any leaks from roof or down walls. coming in and running down the floor. maybe I have a blocked vent somewhere? have caulked the outside to no avail. open to any ideas!!!

thank you

I had leaking windows which didn’t touch the walls. The water wound up in the cabinets in the galley. Water is tough to follow. Windows fixed and so is the problem.

I had a leaking window in the guest berth also. Look there first. Its a PITA to change.

Jeffrey F. Guttelnberger
2005 Mainship 400

I have used alum foil tape successfully to troubleshoot leaking hatches.
I taped perimiter of suspect hatch and used a hose to confirm no infiltration. Then removed sections to ID where the leak was and to determine if I could seal w/o complete removal or it needed rebedding.
If rebedding I highly recommend butyl tape and Compass Marine has a quality tape and how to instructions on how to use it.
No connection... just a satisfied customer and frequent visitor to "Marine How To" articles.

If you don't find a leaking port or hatch I would look next at the rubrail / hull / deck joint. More info w links & pics on the Bacchus site linked in my signature.
Look in the projects section.

MS 390’s are known to need to have the rubrail resealed. Top and bottom. Known defect in manufacturing process.

Alaskan Mainship said:

I have a Mainship berthed in Cordova Alaska - lots of rain. Got to the boat this week and the guest berth carpet is soaked. Main berth has wet floor too (base floor) but not as bad. I obviously have either a leak in the bow and the rain is getting in. no visible sign of any leaks from roof or down walls. coming in and running down the floor. maybe I have a blocked vent somewhere? have caulked the outside to no avail. open to any ideas!!!

Click to expand...

Wouldn't be uncommon to have a leak in the rubrail caulking or the actual deck-to-hull joint... with water entering, running down behind any hull liner or whatever, and pooling in the carpet. Can be complicated by clogged or blocked rubrail drains...

You can test this, to a certain extent. Dry the carpet. Flood the exterior at various places along the rubrail... see if the carpet gets wet again.

If that's it, there can be two levels of fix: 1) just recaulk the rubrail and see if that solves it, or 2) remove the rubrail, reseal the deck joint, then replace and recaulk the rubrail. The first worked once for us on one side of the boat, the second was eventually necessary on the other side.

The rubrail caulk is likely not designed to be the waterproofing system on your boat; more like just a first line of defense...

-Chris

Once you get everything dry, you can put paper towels around wherever you think water may be coming in. The towels will indicate by changing shape if they get wet, even if they dry out you will be able to see that water was leaking there.