Can backplates from bow rail cause moisture?

Marc Rainaldo

Active Member
Apr 18, 2019
260
Netherlands
Boat Info
Sea Ray 500 DA 1994
Engines
Detroit diesel 6v92
Hello all,

Since we have our 500da we have a lot of moisture and leaks in our boat.
I almost rebedded everything on the deck and solve a lot of leaks but still we have moisture especially under the gangway above the ceiling around the back plates from the bow rail.

I completely dried the area around the back plate and spray water on the deck around the foot of the bow rail but no drips of water coming in. After a while all drips around the back plate.

First I thought the water comes from the front of the deck and went slowly his way to the lowest point but that was not the thing. Around 2 foots of the bow rail I have some spider cracks in the gelcoat, but that don’t explain the moisture around the other back plates.

is it possible that the back plates are a thermic cold/heat bridges that causes so much moisture?

If so, what’s the best solution to solve this problem? I was thinking to spray foam over the backplates. I hope somebody experience the same and solve this problem.
 
In a lab setting, there would probably be something "measurable" to what you are thinking. But in reality, no, that's not going to be the issue. If it was, your boat would be the only one in the world I've heard of! :)

The more likely scenario is that the bolts securing the stanchion base plate to the deck are simply due for resealing (caulk).

Butyl rubber is a great choice for this - put a thin layer under the base plate, along with some around the upper thread/under the screw heads. Other sealants/caulk can work quite well, too (don't use 3M 5200, though).
 
With 2 I already did and I used marine sealand. Still around those 2 and the others is still moisture. Before I put the sealand I cleaned everything and used a lot of sealand.
I test for 10 minutes spraying water over the base plate and no water comes in. Couple days later moisture around the plate. Drives me crazy.....
 
It's certainly feasible that a cold, outside rail, could transfer that colder temp to the backing plate (thermic bridge as you mentioned). No question about that.

But the question is why don't we normally see this happening? Maybe it's something we just normally don't see because they are often covered up with a trim piece. And... possibly the "covering up" also prevents the moisture since it insulates the backing plate from the warm/moist cabin air. Could also be something that only happens if the conditions are just right.

I'm assuming these are in locations that are out of sight and have no trim/cover piece? If so, I can't see how trying some spray foam would hurt anything. As long as the moisture completely stops collecting. If it still collects, then you have an issue where the moisture stays there longer and isn't allowed to dissipate/dry out.
 
Marc - what is the humidity level inside your cabin? I would think it would need to be quite high to cause condensation like that...
 
In my first post I used the word moisture but i ment condensation.

The back plates that have area with water drops/condensation are not covered up by interior canvas or something.

the humidity level is now around 65%,
Before i rebedded all hatches, windshielwashers, horn and windshield screws and new screw covers it was 80%, my screen from iPad felt wet at that moment.

now when I open hatches in cupboards I see drops of water (condens) hanging on the ceiling (under the gangway).

even when it not rains then this will happens.

Only thing I can think of is isolate everything with foam.
Never had this on previous boats. But then on my previous boats everywhere on the ceiling we had carpet. Now with the 500 most interior is not direct attached on the sealing. Behind cupboards you can see the polyester ceiling
 
Good question on the humidity level, Carter.

There's the issue, Marc. Fix the humidity level and the issue goes away. Putting foam on those fittings is really only going to be a band-aid in this situation. 65% is still quite high. It'll likely cause other issues down the road if not addressed.

What's causing the high humidity?

You dealt with a leaking water tank a while ago. Could there still be water lingering in the boat?

Are you using your HVAC system? Maybe you need to run a dedicated dehumidifier, as well?
 
I have still doubts having water in the bottom of the boat. The boat is also hanging to port side.
I checked pictures of the previous owner and pictures from couple years old the boat was ok. Pictures from last year I saw the boat hanging to the port side. I am afraid that because of the watertank and multiple leaks the water went to a hidden place at port side.

when I open a hatch in cupboard on star port side I can see the hull all the way down. On port side I can’t see al the way down. In guestroom there is also a hatch in floor and the space is around 2 meter long to the bow. This space is flat so it means that there is a space under it, the same as under bathroom guestroom. But I can’t reach it. Maybe I have to drill a hole.
 
I don’t use the ac system on heat functions. I use a separate electric heater
The AC system will dehumidify the area. A portable electric heater will not. Some of the systems that Sea Ray used even have a separate "dehumidify" setting to work even faster. Check the control board/manual or google for the manual.
 
When the weather was warmer we use the ac a lot. Now it’s colder and we put the ac at heater there is a bit of strange smell (according to misses ) , so that’s why we use a electric heater.
 
Have you rebed the hatches? Water can leak in and be soaked up in the foam of the ceiling and wall vinyl. Does it look like any of the ceiling vinyl is puffed out or not attached to the deck?

On a prior boat, about 15 years old, I decided to rebed the hatches from a preventive maintenance standpoint. There was no moisture problem with the deck, but there was water soaked into the foam backing of the ceiling vinyl. I dried everything out and used an adhesive spray glue to reattach to the underside of the deck. I the sealed the hatch cut out and rebed the hatch frame.

It’s interesting that the Admiral and I felt like it was very humid in the master stateroom for the past season. Fixing this fixed that humidity issue also. Lucky I fixed it when I did.
 
On many places the vinyl on the sides are wet :(, ceiling vinyl seems dry.
The hatches i removed from outside. The vinyl I didn’t touch. After rebedding, with inside frame removed, I checked evrything with spraying water all around the hatch and no leaks anymore.

1 question about the ac, I thought that ac Dehumidify only when it operates on cooling. On previous boats we also used an electric heater and never had this problems. I read the manual and when programmed dehumidify mode the system first use the fan for couple minutes and then cooling to dehumidify and stop, after couple minutes he repeat same process.

at the moment is 8 degrees in daytime and around 1-2 at night.
 
You're right that the main dehumidification comes from cooling mode - and reading back over my post, I wasn't very clear. When in heating mode, there is some decrease in relative humidity from the warm air it's producing... or, at least that's way I've always understood it. But maybe someone with better HVAC knowledge can explain it.

If your temps are running that cold right now, then that brings us back to the humidty must be coming from inside the boat. Especially since you've said you've had other boats (I am assuming that the only real variable here is the boat you've had) and haven't seen this issue.

I think until you can get the interior humidity level (problem) figure out, you're going to be dealing with this for a long time. In the meantime, you might want to get a separate dehumidifier and run that.
 
When the weather was warmer we use the ac a lot. Now it’s colder and we put the ac at heater there is a bit of strange smell (according to misses ) , so that’s why we use a electric heater.

I think something is wet in side the boat or water is trapped somewhere. As for the smell in heat mode, it should work well unless the water temp. gets below 45-50*f. If it smells, something is wet, dirty or both.
 
Tomorrow I gonna check if I can reach the hidden area because humidity lvl is to high and the boat is listing to port side. I also will turn on the ac in heating mode with open hatches. Monday or Tuesday I pick up a dehumidifier from home.

True what you mentioned about dealing for a long time. since we bought this ship, the most effort we did had to do with the humidity lvl, found many leaks, humidity percentage is increasing but still a lot of condensation, really drives us crazy sometime.... needs a solution.
 
Today the weather was sunny for a change. We opened every hatch and run the salon airco in heat modus until 15:00
Then I also closed all hatches.

In the guestroom we had couple days ago drops of condensation water hanging on the vinyl. In the morning I dried that. On 15:00 i turned on the airco in guestroom in heat modus. i read the manual about dehumidification program and around 16:00 I put guestroom in dehumidification mode. At several periods of the day I touched the vinyl and it’s getting dryer. The program blows cold air.

We can’t run all airco at the same time because we have only 16ah shorepower. The generator I already winterized.

Tomorrow it’s gonna be a rainy day again so can’t open all the hatches the way we did today but I shall put the salon airco in dehumidification mode.

Unfortunately the airco panel in masterbedroom is mall functioned. I can only cool there. This is the panel, because i switched the panel couple weeks ago from the panel in the salon to test and want to have the heat modus in salon.
Problem is that in masterbedroom on many places the vinyl and carpet is still wet so maybe I have to swap the panels again.

I also checked everywhere to see a opening for hidden areas but couldn’t find any. Maybe best thing is to write sea Ray for a drawing of bulkheads under the floor before drilling a hole.

I was surprised how fast the condensations disappeared in guestroom. Yes we had a long period of constant raining so I must admit we didn’t open the hatches often. Maybe it’s still ‘old’ moisture from previous leaks that couldn’t get out by our separated heater and maybe this 500 is completely different to handle......
 
Marc - there is a company here called Flight Systems (http://www.flightsystems.com/). They fix the CruiseAir SMX control panels. I have not used them, but some here have and seem to be very pleased with their work. You might want to contact them about your inop controller...
 

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