rain water leak into bilge

T

thedoo

New Member
Apr 29, 2023
18
Boat Info
2006 340 dancer
Engines
8.1l twins
2006 340 dancer. i have been trying to trace a water leak for the life of me cant find it. I put dye in the water system to eliminate that no leaks checked engines under full load on the lake no leaks. boat stays bone dry in bilge till it rains. then i get about 2 gallons of water in it starts on port side upper stringer then travels down the drain passages to the lowest part of the bilge. i caulked the arch seems and around the side vents. i checked the inside of the arch bone dry. its driving me nuts. i have looked around everywhere with no luck. i have even sat in the bilge when it rains but dont see anything bullet proof. best i have seen is a small trickle from the front upper port stringer where the bath hoses come through the wall but it wasnt much. anyone have any ideas?
 
My theory...yet to be proven.

Have you checked the aft port/starboard corners where the lower hull shell overlaps with the upper hull...best viewed from inside the bilge/ER? You may see water streaks from these corners running down the ER wall to the bilge. On the exterior this is where the rub rail runs along the line of the hull.

My hypothesis is that rain runs down the rub rail (and behind the rub rail when the sealant fails) to the back corner and enters the overlapping hull sections via the screws that fix the rub rail to the hull. These screws do not appear to be installed with sealant. The overlapping halves appear to me to be non-cored, fiberglass tabs pierced by the screws.

Screenshot 2023-07-26 183014.png


It may be different on the 340, but something worth checking. Please let me know if you find water streaks at the aft corners.
 
Magic said:
My theory...yet to be proven.

Have you checked the aft port/starboard corners where the lower hull shell overlaps with the upper hull...best viewed from inside the bilge/ER? You may see water streaks from these corners running down the ER wall to the bilge. On the exterior this is where the rub rail runs along the line of the hull.

My hypothesis is that rain runs down the rub rail (and behind the rub rail when the sealant fails) to the back corner and enters the overlapping hull sections via the screws that fix the rub rail to the hull. These screws do not appear to be installed with sealant. The overlapping halves appear to me to be non-cored, fiberglass tabs pierced by the screws.

View attachment 148439

It may be different on the 340, but something worth checking. Please let me know if you find water streaks at the aft corners.
Click to expand...
I will check this out, as I thought it could be the rub rail issue. I just baffled I can't see it.
 
Follow me on this.
Is the water in cabin? No.
Is water causing mold? No.
Is water in bilge? Yes.
Do you have working bilge pumps? Yes.
Are they connected to constant source of power when you not there? Like good batts and shore power batt charge? Yes.
Stop driving yourself nuts.
 
thedoo said:
I will check this out, as I thought it could be the rub rail issue. I just baffled I can't see it.
Click to expand...

My 370 is of similar design and the same hull. I get rainwater at the exact rubrail corner that was mentioned above. I resealed the top of the rail at the rear corners and it helped but didn't eliminate the issue as water can get inside the rail at the high points of the boat and run down. I plan to seal those screws this winter.

Another thought to look at is your rudder shaft seals. I had to tighten my port side seal up this spring due to it dripping.
 
Pirate Lady said:
Follow me on this.
Is the water in cabin? No.
Is water causing mold? No.
Is water in bilge? Yes.
Do you have working bilge pumps? Yes.
Are they connected to constant source of power when you not there? Like good batts and shore power batt charge? Yes.
Stop driving yourself nuts.
Click to expand...
Some of us are not as chill, laid back as you are :)

This would drive me nuts as well until I found the source.
 
stg099 said:
My 370 is of similar design and the same hull. I get rainwater at the exact rubrail corner that was mentioned above. I resealed the top of the rail at the rear corners and it helped but didn't eliminate the issue as water can get inside the rail at the high points of the boat and run down. I plan to seal those screws this winter.

Another thought to look at is your rudder shaft seals. I had to tighten my port side seal up this spring due to it dripping.
Click to expand...
I did both rudder packings as they were leaking earlier in the season. They are dry as a bone
 
Pirate Lady said:
Follow me on this.
Is the water in cabin? No.
Is water causing mold? No.
Is water in bilge? Yes.
Do you have working bilge pumps? Yes.
Are they connected to constant source of power when you not there? Like good batts and shore power batt charge? Yes.
Stop driving yourself nuts.
Click to expand...
I don't settle for anything less than perfect. Sorry it drives me nuts. Since I have owned this boat I have fixed everything to proper working condition no matter how small the problem. I am ocd to the highest level.
 
stg099 said:
My 370 is of similar design and the same hull. I get rainwater at the exact rubrail corner that was mentioned above. I resealed the top of the rail at the rear corners and it helped but didn't eliminate the issue as water can get inside the rail at the high points of the boat and run down. I plan to seal those screws this winter.

Another thought to look at is your rudder shaft seals. I had to tighten my port side seal up this spring due to it dripping.
Click to expand...
I am.gonna caulk the entire rub rail and take it from there.
 
Maybe place some blue shop towels in the bilge, around where the rubrail is mounted, take a garden hose to the outside, see what you see. Could purchase a water meter/detector as well.
 
Magic said:
My theory...yet to be proven.

Have you checked the aft port/starboard corners where the lower hull shell overlaps with the upper hull...best viewed from inside the bilge/ER? You may see water streaks from these corners running down the ER wall to the bilge. On the exterior this is where the rub rail runs along the line of the hull.

My hypothesis is that rain runs down the rub rail (and behind the rub rail when the sealant fails) to the back corner and enters the overlapping hull sections via the screws that fix the rub rail to the hull. These screws do not appear to be installed with sealant. The overlapping halves appear to me to be non-cored, fiberglass tabs pierced by the screws.

View attachment 148439

It may be different on the 340, but something worth checking. Please let me know if you find water streaks at the aft corners.
Click to expand...

my boat proved this one for you in 2020

pics of reseal are in my thread
 
Magic said:
thanks SC…as I suspected!
You went to a lot more trouble to reseal than I had envisioned it will take. Not looking forward to this job!

thanks
Click to expand...

anything worth aggravating myself over is worth spiraling all the way into the pit of rage over.

that way I don’t have to do it 2/3 of the way, twice! :D
 
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