Leak from bow thruster

[Capt’nKarl]

I have a mysterious water leak. While out on our last adventure I discovered water collecting in the area forward of the shower sump pump. It wasn’t a lot of water, maybe 1 liter, but water coming in nonetheless. Now back on the trailer at home I’ve had the chance to further investigate. I found, felt some dampness around the bow thruster tube. I suspect that’s where this leak is coming from. I did use the thruster quite a bit on our outing which adds credence to my leak theory. Is there a gasket between the thruster motor and the tube? Has anyone else had this happen? Do I need to pull out the thruster? Thanks for your help.
Karl

 

[Anna]

The first thing that I would check is the drain hose from the anchor locker. It is accessible by removing the panel holding the mirror at the front of the Vberth. Hope this helps.
Russ

 

[Capt’nKarl]

Thank you Russ. The anchor locker was emptied and the drain checked. It’s patent so there’s no issue there. While stationary in the water I was able to visually see water seeping into the Vee area of the hull, at the point of the bow thruster, then down to the shower sump pump area while we were underway. Again, it was not much water but that area should be bone dry. That’s why I think the seepage has something to do with the thruster.

 

[Brian B]

Perhaps the thruster leg is leaking. I recently removed my Sidepower bow thruster leg. On the Sidepower there is a gasket between the leg and the tube that is assembled with sealant.

 

[Capt’nKarl]

Thanks Brian. I’m pretty sure this is the source of the leak. How difficult was it to remove the thruster leg.
Karl

 

[Irish Mist]

If you remove the thruster motor there are two bolts you can try tightening. You can do that with the boat in the water. But chances are if it had been leaking you may need to pull the boat and replace the gasket. But I would try tightening first .

Good Luck

 

[Brian B]

Thanks Brian. I’m pretty sure this is the source of the leak. How difficult was it to remove the thruster leg.
Karl

We have different boats so not sure if my experience would be the same.. On the Sidepower two bolts hold the motor. When the motor is removed two bolts go through the motor support through the tunnel into the gear leg. The old sealant gave me a problem removing the gear leg.

 

[Mr Ben]

I have a 2016 25sc. When I launched the boat this spring the bilge pump kept running so I obviously had a leak. It seemed to be coming from the rear thruster. I pulled the boat back out made a few calls. I found a skinny helper we removed the rear thruster. When I pulled the last bolt out the tunnel fell to the ground. The silkflex had lost its bond to the tunnel. I had purchased a new gear leg gasket from Imtra. I cleaned everything up, roughed up the surfaces with sand paper and put it all back together with 5200 per the factory advise. No more leaks. It was a 4 hour job start to finish, with at least that much time researching and procuring parts. I hope I never have to do that again. It really helps to have a flexible skinny friend. I do not have first hand knowledge of the front unit. But these things can and will leak.

 

[Brian B]

Imtra specifically told me NOT to use 5200. They suggested Silkaflek or Lifeseal.

 

[Mr Ben]

Imtra told me to use 4200 on the gear leg. I had sent an email to RT also. Ken Marrs actually called me, he told me to use 5200 between the hull and the tunnel. I disagreed as the plastic tunnel pc is like $600 and probably would not survive removal again. He strongly suggested I use 5200. I guess mine is not the first with this issue. I did let it sit for 5 days after the repair before relaunching. All is well.

 

[S. Todd]

(not to hijack this post but it already migrated to the stern thruster) A few years back we also developed a leak in the mounting between our stern thruster housing and the hull on our 2015 R25. Upon disassembly we discovered the holes drilled through the transom for the mounting bolts were not done exactly per the template and a few of them were at angles rather than straight. A few of the stainless bolts where actually bent upon assembly due to the misalignment of the holes. This prevented the assembly from fitting perfectly against the flat surface of the transom and caused a leakage once the sealant aged a few years. I cleaned up all the old sealant, straightened out the holes drilled through the transom and reassembled with 3M 4200 (based on factory recommendation at the time). Once the bolts had nice straight pulls to tighten the assembly against the transom, the fit was good and the seal was tight, no more leakage. The skinny friend with long arms made the task bearable.

 

[Mr Ben]

I had the same issues with mine. Bent bolts and the washers on the inside were under size IMO. Some were sunken into the transom. I used new bolts and stainless fender washers. I think it never really sealed properly then a few years of moisture getting behind the then freeze thaw cycles, it finally failed. Sorry to expand the thread just wanted to share my experience . There was little info to be found when I was dealing with it. I think the thruster is the same location and mount is different up front. Now on to the bilge pimp wires wrapped around the prop shaft.....

 

[Capt’nKarl]

I took the boat out today specifically to look for a possible bow thruster leak…and I found it. Sitting in the calm water there was no evidence of any leak but once I started using the bow thruster a drip…drip…drip…appeared. Guess I’ll have to pull the motor and reseal the unit. Ahhh, another project to add to my list. I have to keep reminding myself it’s a boat.