MS 390 - Bilge pump for swim platform

[Lshulan]

On my 2002 MS 390, the swim platform fills with water after awhile and while there are access ports allowing me to pump out, until pumped, I’m dragging hundreds of pounds of water around. The PO had removed the top skin and took out all the foam, added the access ports, etc following Mainship’s procedures, but it still leaks. I can’t see where the water is coming in from so until the next haul out (where I will try to correct the leak), I’d like to put in a small bilge pump (which is what I understand Mainship suggested). Anyway, if you have such a setup, where does the discharge exit? Any suggestions would be welcome

 

[SIBERNUT]

Tape it shut with the shrink wrap tape. Sticks like glue, no residue when removed and wide

 

[Comodave]

Just get a small automatic bilge pump. Mount it down low and run the discharge hose up above the waterline and put a thru hull in. Then run power to it.

 

[Lshulan]

Sibernut- I think I didn’t explain properly, the PO removed the top, took out the foam and replaced the top lid and caulked it properly. I’m asking about where to have the discharge for the bilge pump

Comodave - specifically where to exit above the water line? Do you mean above the waterline in the swim platform or in the engine compartment?

 

[Comodave]

I would run the discharge hose up near the top of the swim platform and have the water exit there, not into the engine room. Keeping the discharge hose shorter that way. I use rare earth magnets to find where to drill. Get 2 powerful ones. Tape one on the inside where you want to drill and then go outside with the second one. The second one will stick to the first one that is taped inside. Then mark where the second one is and drill the hole. No measurements necessary.

 

[Lshulan]

Comodave - my only concern is that underway, the waterline on the swim platform drops and while I have actually taken a close look, it may be under water since the stern sits down quite a bit underway. I will take a good look at it next time out to see

 

[Gdavid]

I would run the discharge as high as possible out the back of the platform, you will likely need to create a flat spot due to the shape of the platform under the rubrail.

On my father's 390, the leading edge of the rubrail was catching water as it was underway, filling the rubrail with pressurized water looking for any gap to squirt in. We fastened the lid and then caulked the gap of the rubrail on both sides. It gets much less water inside now. Manageable periodically with a hand pump.

 

[johnma]

Sibernut- I think I didn’t explain properly, the PO removed the top, took out the foam and replaced the top lid and caulked it properly. I’m asking about where to have the discharge for the bilge pump

On the original repairs performed by Mainship there was either a bilge pump installed that dumped the water into the main bilge, or they drilled a port from the platform into the main bilge. Mine was done by Mainship and I have the port in mine.
There is a drain plug in the bottom of the platform to empty the water out when you pull it for the season. I used to get about 2-3 gallons out every year. I started looking and the seam where the cover mounts to the transom wasn't caulked very well. I recaulked it and now i get maybe a pint of water when i remove the plug.
a while ago someone posted the original drawings from Mainship for the repair showing the location of the port into the main bilge. I think it was on the Mainship owners group on facebook

 

[Lshulan]

Today I pumped out the port side of the swim platform in anticipation of installing a bilge pump expecting the starboard side to drain over, but I was in for a surprise. The starboard side is still sitting with about four inches of water and the port side is bone dry (after pumping out several hours ago). Are the two sides totally isolated by the swim ladder portion? If so, do I need two bilge pumps (or two drain holes to the bilge if I go that route) ?

 

[Comodave]

Is there a way to drill a limber hole from the side that is still wet into the area with the pump? If there is drain the wet side first then drill the hole. If you go through wood you will have to line the hole with something like PVC and seal the edges or epoxy coat the wood really well. Probably after drilling the hole dam up the lower side and pour the epoxy in the upper side and let it soak in for a bit before pulling the dam and letting the epoxy run out. Don’t wait too long because the epoxy could set up.

 

[Lshulan]

I’m reluctant to be drilling holes into an area where I don’t know what’s on the other side. So am hoping someone on this forum who has has actually solved this issue this way.

 

[Comodave]

I’m reluctant to be drilling holes into an area where I don’t know what’s on the other side. So am hoping someone on this forum who has has actually solved this issue this way.

I don’t mind drilling holes in your boat…. What I do when I am not sure what is on the other side or to locate holes to be drilled is take 2 very strong rare earth magnets. I tape one where I think the hole should go and then go to the other side with the second magnet and see where it sticks. Hole located. I have used this to find stanchion bases, tape one next to the base on deck and go below with the second magnet and it will find the stanchion base. The PO of our boat hit something very hard with the bow rail. It bent the rail and broke 3 bases loose. I had to find where the bases were inside above the headliner and the galley cabinets. I had to cut some holes in the tops of the cabinets to get to the backing plates for the stanchions. I didn’t want to cut any more than necessary.

 

[Lshulan]

Comodave - I understand and this is certainly a good way to do it. But since I have limited access and as you pointed out, not just drilling holes, also making sure the edges of the hole is epoxied so I don’t create a new problem, this is going to wait until haul out. But I’m also hoping to hear from others that have either fixed it themselves or are able to explain what Mainship did specifically. For example, a previous post referenced drilling a hole so as to drain into bilge and another suggested a bilge pump in swim platform to pump into bilge, but do these allow drainage for both sides or is a hole between them needed?

 

[Comodave]

Yes, I have never seen what the inside of your platform looks like. Too bad Mainship isn’t around anymore to ask.

 

[fgarriso]

Today I pumped out the port side of the swim platform in anticipation of installing a bilge pump expecting the starboard side to drain over, but I was in for a surprise. The starboard side is still sitting with about four inches of water and the port side is bone dry (after pumping out several hours ago). Are the two sides totally isolated by the swim ladder portion? If so, do I need two bilge pumps (or two drain holes to the bilge if I go that route) ?

Don't do anything, and I will be right over with a industrial hole saw to cut as many holes in YOUR boat as possible.

 

[Comodave]

Don't do anything, and I will be right over with a industrial hole saw to cut as many holes in YOUR boat as possible.

Wait a minute, I am first in line to do that… See post #12.

 

[fgarriso]

Wait a minute, I am first in line to do that… See post #12.

Dave,
Your right, But I have a 4" and a 6" hole saw

 

[Comodave]

I think I have a 6.5” hole saw. And I have 2 reciprocating saws too…

 

[DrissZougari]

My MS390 was done at Mainship and I have one bilge pump on starboard side with discharge above water on the platform. I also know that the port side is draining into the starboard side via a passage in the platform construction and not newly created hole. I could take few pictures for you tomorrow if you like (just text me directly). I used to have more water inside the platform that I resolved by properly caulking both hatches properly.
(252)721-4262

 

[fgarriso]

Dave,

OK you win. You can cut the first hole.

 

[Comodave]

You can do the second hole then…