Aft drainage boxes on a 390

I'm wondering if any other 390 owners have had leakage issues with the aft drainage collection boxes. I've searched the forums for a thread about this issue but no luck. In short....the box on the starboard side of my boat, glassed to the inside of the hull, leaks into the boat at that joint when water enters the box through the hull opening (wave action). Two hoses use that box to drain overboard: the starboard flybridge deck drain and the aft bilge pump. I have tried many times to fix it, to the point where I'm considering sealing it off and running the hoses to two new thru hulls further forward (where I can actually
get at the hull side). I'd rather not resort to that, but it's totally inaccessible from the inside, without removing the water tank and exhaust hose All attempts at fixing it thru the hull opening have failed, though they did slow it down a bit.
I'd appreciate any advice I can get on this one.......I've run right out of patience!

Nick, I am looking at a 2005 MS 430 aft cabin with the same issue. When we turned the battery switch on yesterday at the survey, the bilge pumps came on and the ‘chest’ started to leak bilge water back into the hull. It looks like the glassed in box failed and the fluids appears to be leaking from the top and bottom seam where it’s glassed to the inner hull.

It’s a PITA to get to, as you have to crawl over the transmission and muffler of the starboard engine.
I did consult with a Mainship dealer today who indicated they have seen this, but was not aware of the fix.

An ideas anyone?


JimL

Jim, the "chests" on my 390 are quite deep, well below the level of the outlet hole, and there's no drain. I'm wondering if ice pressure during winter layup broke the bond to the hull. I've looked at a later model Mainship (Pilot), same drainage arrangement but the chest bottom was almost flush with the outlet hole, which makes me wonder if it was a known design defect. I wish mine was a PITA to get to......it's just impossible!

jimL said:

Nick, I am looking at a 2005 MS 430 aft cabin with the same issue. When we turned the battery switch on yesterday at the survey, the bilge pumps came on and the ‘chest’ started to leak bilge water back into the hull. It looks like the glassed in box failed and the fluids appears to be leaking from the top and bottom seam where it’s glassed to the inner hull.

It’s a PITA to get to, as you have to crawl over the transmission and muffler of the starboard engine.
I did consult with a Mainship dealer today who indicated they have seen this, but was not aware of the fix.

An ideas anyone?


JimL

Click to expand...

JimL

The 430 you are considering seems to have a few build issues, referencing the windlass area as well. Some have walked from potential purchases for lesser reasons, worried about the tip of the iceberg concept. I know I have, on some storied name brands.

We took possession of the vessel a week ago and moved it thru the Seneca and Erie Canals, and Hudson River over the past three days. A wonderful trip and a few small minor gremlins but nothing serious. Most of the initial issues we resolved, except the drainage collection box. The PO tried to fix the leaks and was marginally successful, but not 100% - it still leaks from the bottom of the inside drain area. Also the center starboard scupper will not drain water despite me snaking over 30 inches of tuning downtime scupper.

Any ideas on how to ready this for the aft drain collection box? the forward starboard one has no issues.

JimL

I gave up...

Jim, I have now blocked off and sealed that collection box. The flybridge drain and aft bilge pump now have their own thru-hulls under the lower helm. Hose routing was a bit challenging, and the first time it rained I found out the starboard transom locker drain was tee'd into the flybridge drain, since it filled up with water. Now I'll need to run that line over to port and tee it into that transom locker drain, which appears to have no issues sharing an outlet with the port flybridge drain. Maybe then I'll be done playing musical drainpipes!!!

Are you sure it's not the hoses that are leaking? I had the same issue on our 390 port side and discovered the the hose from the flybridge scupper came off the tee. Luckily I'm fairly skinny and was able to crawl over the water tank and reach the fittings and then reconnect everything along with double clamping the hoses. Mine only had one hose clamp on each hose. I had leaves and debris build up over the winter in the port side scupper and used a plunger to clear the clog. with only one clamp, the plunger worked but also popped the hose off of the tee.
John
2003 MS390

John, Based on the work the PO did, that is my next step. Crawl over the engine and muffler and see for myself what the issues are. My starboard side forward scupper drains slowly but ok into the FWD drain box, while my starboard side aft scupper does not drain despite me snaking it with a flexible tube. Your diagnosis may be on target. I'll get in there this weekend and see for myself. It's a tight fit!

Jim

make sure you're not alone on the boat when you crawl in there. If you get stuck you might need someone to grab your legs and pull you out. Don't ask how I know this

John

LOL! I know it's a tight fit!