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Rain blowing in through engine compartment vents

PostPosted: Tue Sep 12, 2017 11:12 am
by Nolan Bonney
We have owned NT 42-31 built 2001 since 2015 and have found fresh water in the engine bilge following a rain/wind on a number of occasions. I believe rain water is being blown into the engine compartment vents as we have found the plywood cabin floor has absorbed water and is delaminating. I'm interested to learn if any one has encountered this issue and how it was resolved.
Thank you,
Nolan Bonney

Re: Rain blowing in through engine compartment vents

PostPosted: Sun Sep 17, 2017 8:28 am
by Sam Landsman
If your 42 engine room vents are like the vents on my 37, the rain would have to be really heavy and the wind really strong to get into the engine room. I've had a couple of times where seawater got through the vents, but those have been in situations of heavy spray. Think crossing Rosario with southerly wind gusting to 50 knots and sheets of spray covering the boat almost constantly. I spent two days in Ketchikan in August with 15-20 knots of wind on the beam and 10 inches (it was a wet summer!) of rain and didn't have any rain make it into the engine room.

If you've got fresh water in the bilge, have you double checked the whole domestic fresh water system for leaks? The sink and shower drains? Does the P&T valve on your water heater dump (or leak) into the bilge or through a hose overboard? Is there a path for water to run forward from the lazarette to the engine room? If you turn the pump off and leave the boat for a week, when you come back, does the pump cycle on immediately indicating loss of pressure in the system?

Deck hardware could also be the culprit. Sealants fail over time (17 years seems to be about the time on my boat) and all the deck hardware eventually needs rebedding. Could the water be coming from the rail or cleats? I supposed the sealant around the engine room vents could also be a source of leaks.

Leaks can be tricky to find. Good luck and let us know what you find out.

Re: Rain blowing in through engine compartment vents

PostPosted: Fri Oct 13, 2017 4:15 pm
by Dave Starrett
I would say, that you have a rub rail that needs to be rebeded. Look at Bill Robertsons post and my reply on March 25, 2014 under maintenance. Wind with hard rain or lots of heavy water over the bow will find any openings that might exist in the deck to hull seam that hides under the rub rail. On the NT 42 that seem is only a butt seam. The factory glasses the seam in only a few places on the inside of the hull. Your problem sounds very similar to mine.

Re: Rain blowing in through engine compartment vents

PostPosted: Sat Nov 04, 2017 1:30 pm
by Paul Downes
We also have the problem you have described on the starboard side of our 42-27. I removed the joint rub rail and caulked the whole seam after our cruise this year to no avail. The original caulk was spotty in places so I had an aha moment and hoped for the best. I did not consider the engine room vents and wonder if you had any luck? The amount of water seems to be more than would come through a leaking rail mount but who knows. Please keep us informed of any progress.

Re: Rain blowing in through engine compartment vents

PostPosted: Sat Nov 11, 2017 3:29 pm
by Randy Wickers
We have fresh water in our 42 bilge, but it's only after we replenish the water tanks. I asked Nordic Tugs about this, and the theory for our situation is a loose hose connection or a malfunctioning overflow vent. Unfortunately it's not possible to access the hose without major surgery through the hull. There's no access from inside.

Randy Wickers
Time for Two NT 42-030

Re: Rain blowing in through engine compartment vents

PostPosted: Mon Nov 13, 2017 11:20 am
by Gary White
Just a wild guess here but have you checked to see if it might be the pressure relief valve on your hot water tank?