Mental jujitsu on dealing with the water intrusion on Mainships 350/390 swim platform

Sorry long winded title.
I am posting this in open forum rather than the Mainship forum because I am looking for broader ideas.
That said I know what the permanent fix is for the Mainship 350/390 swim platform taking on water and soaking the foam inside. Rather than tear the platform open, remove the foam reseal the platform and install hatches that I find ugly. I am looking at a dewatering solution that I can perform several times a year depending on the amount of water that actually seeps inside the swim platform.
I was thinking if I can drill/cut a hole in each compartment (3) large enough for a hose of sorts attached to a pump and pump out the water in each compartment on a regular basis. Maybe a vacuum type pump that could pull water from the foam after it removes any standing water. Then install a hole plug and every twice a year repeat the dewatering process. I am right now not interested in the permanent fix but rather just to de-water the compartment.
What say you
Thanks in advance
Jim

Greetings,
Mr. jc. Depends on how freely the foam releases he entrapped water. IF it took X years to soak up it may take the same to dewater. Good idea, though…

like I said "Mental jujitsu"

As said above, it depends on the type of foam. Some don’t release the water easily. I think I would bite the bullet and remove the foam. I use a flexible drill extension and a drill bit on it to chew up the foam. At least to cut it into pieces that can be removed.

Im not in the mood to remove the top of the whole swim step and dig out the foam. The boat will have to be on the hard to do that kind of work.
As I stated in the post looking for ideas on de-watering other than the permanent fix.
Even a do it yourself yard local in Southern California is two months rent up front = $4,000. the only other yard is 1,800 to haul out, $200.00 to block and $180.00 a day. Plus foam disposal of 12 lawn and leaf bags worth. That's do it yourself.
Looking for Ideas to de-water. The permanent fix will come latter when I can afford to have it done.
Were talking approximately 12ft long by 2ft deep its part of the boats running surface, by 30" wide.
Most people install 3 large rectangular hatches to remove the foam.
I think its ugly and a trip hazard.

What if you put two holes in each chamber and installed a tire valve on one of them. Then forced compressed air into the "in" hole, and the water gets blasted out of the "out" hole ??

Benthic2 said:

What if you put two holes in each chamber and installed a tire valve on one of them. Then forced compressed air into the "in" hole, and the water gets blasted out of the "out" hole ??

Click to expand...

Interesting
A buddy of mine is going to lend me his vacuum pump that he used to use to evacuate water from large refrigeration units. I'll need to install a Schrader valve into the swim platform and connect the pump. Then gauge how much water comes out.

Need more ideas! Anyone else?

I think vacuum is the right idea but rather than using a refrigeration vacuum pump (low volume), use a large shop vac and vacuum moisture up every couple of feet or so. You'll need to drill a few two inch holes. Heck, use three shop vacs in parallel....Use access ports to cover holes until the next time.

gsholz said:

I think vacuum is the right idea but rather than using a refrigeration vacuum pump (low volume), use a large shop vac and vacuum moisture up every couple of feet or so. You'll need to drill a few two inch holes. Heck, use three shop vacs in parallel....Use access ports to cover holes until the next time.

Click to expand...

That popped into my mind today. However I only thought of one vacuum

Put hole in bottom for regular drain plug. Then Schrader valve close to stern out of way. Make them as far apart as possible, and only force a little air in. It will push water out. Shop vac will burn up pretty quickly.

Too much air blow the seam. Think working it at least a week.

You're not going to get the water out of the foam. You're going to need to remove the foam. You can remove the entire top, hog out the faom, then reinstall the top. I would install the hatches. I have a bilge pump and a float switch in there.

Maybe something like this:
http://www.hotvac.com

Hey Jim,

I know nothing about your boat. But, it sounds like you have three problems: (1) Water finds its way into voids in the swim platform, (2) it is hard to get it out, and (3) the glass has come loose from the core.

I had a similar problem with my forward deck when I bought the boat. I used an injectable 2-part polyurethane to adhere the core that had come loose from the glass, while displacing and filling any small pockets of water or other voids and chemically incorporating and remaining small quantities of moisture or water.

The repair was relatively straight-forward, done in a couple or 3 half days, and is as good today, about 2 years later, as it was the day it was done.

Pictures are here, I've also attached a recent one I happen to have on my phone.
-- https://drive.google.com/folderview?id=1PmduxDyL6BMa4Ax4uPQ3NfPZDzRI0oI5

At the time I did a write up here:
-- https://www.trawlerforum.com/forums/s32/high-density-polyurethane-foam-deck-repair-46818.html

The product vendor, who.provides great tech support to boaters, is here:
-- https://injectadeck.com/

A non-marine supplier of a suspiciously similar product is here:
-- https://emecole.com/foundation-crac...uctural-reinforcement-polyurethane-injection/

I always like to caution to read the cautions and have reasonable expectations of the limits. The stuff can over expand and damage things, nothing is magic and seemingly exaggerated claims are likely just that, etc. I fixed a relatively minor problem before it became major. I doubt I'd have been as happy if I expected to reinflate and make rigid floppy failed decks.

Cheers!
-Greg

Dissolve foam and drain out thru garboard drains installed at low points. test a sample for a non explosive solvent that will dissolve it. Do the job right the first time.

What we did with our MS 390 13 months ago...

My wife and I pretty much decided on the Mainship 350/390 after 18 months of looking and lots of research. We heard many of the horror stories about the swim platform manufacturer's defect, which was fixed in several different ways early on... sometimes well, and sometimes not very well. The story of how this appendage came to be added on (early on) to the original design is also interesting. But I'll stay on topic in an attempt to keep it short. One 390 we looked at, the owner boasted, "And I've already had the $8,000 swim platform problem fixed!"

Most of the MS 390s we looked at already had the fix done, which was to remove the top of the swim platform, remove all the foam, put on some additional fiberglass where water intrusion is suspected, and some even provided a drain hole through the transom into the bilge (?!). Most repairs including the addition of 2 or 3 inspection ports in order to see what is going on in there, and pump out water occasionally if there was no drain hole to the bilge. The foam and a gabbard plug was the manufacturer's idea of a warranty repair for the defect... to prevent the [large] cavity from filling up with water.

The 2000 MS390 we ultimately ended up still with had all the original foam, and a gabbard plug that was removed every fall (as if that was a fix!). The original owner did not think the problem was a major problem and did not bother to fix it. The second owner = Same. I had heard all about this from LOTS of owners and surveyors, and I was no longer "horrified" about the defect. "It is a manageable defect."

Fortunately, I learned of a fiberglass guy who had fixed this problem "the right way" on 2 or 3 Mainship 390s in the past in nearby Rhode Island. For $4000, the guy would remove the top, clean out all the foam, remove the gabbard plug and fiberglass over it, do any additional F/G that was needed on the inside. There was a small yard fee for hauling it and all.

We wanted the fix done right for our "new" home / boat; we negotiated the work as part of our offer, and hours after closing on the boat our F/G guy went to work. He was done in a week, over 15 contractor bags of foam were removed, as he predicted. He put a nice piece of molding along the transom on top of the swim platform, and he also did a few other things for me. I did not want a drain hole into my bilge. So he did not do that. My plan was to use a Seaflo "Dry Bilge System" product which is designed to get the last inch of water out of any place on a boat, if needed.

Today, I know dozens of Mainship 390 owners, each have managed this in slightly different ways. None, including us, think this is a deal breaker for a boat that is very well built and well thought out in design in so many other respects. It is a very popular "Looper" boat, as we have learned on the Loop ourselves.

My advice is to get it fixed right. Pop the top, get the foam out, come up with your plan to evict any water that makes its way in there. It would be nice to find someone who has done the job before. If you happen to be near RI, I can help you with a guy's contact info! If you opt to simply live with the problem, you won't be alone... you'll be in the minority, but not alone. The Seaflow "Dry Bilge System" might help you either way. I've learned the pump is not very resilient to frost. But it does the job, and it isn't expensive to replace if it fails. It IS good at getting the last 1/4" of water (or less) out of that area (or any other.)

On this trip, I have talked with many owners of much more expensive boats, including Grand Banks, Sabre, etc. They all have stories of known manufacturer defects that have and how they manage them.

Comment removed. I misunderstood one of the posts, so my comment made no sense. Sorry!

(There is no way to get all the foam out without removing the top of the swim platform... way too much material.)

I like this but........

Capt Ray said:

My wife and I pretty much decided on the Mainship 350/390 after 18 months of looking and lots of research. We heard many of the horror stories about the swim platform manufacturer's defect, which was fixed in several different ways early on... sometimes well, and sometimes not very well. The story of how this appendage came to be added on (early on) to the original design is also interesting. But I'll stay on topic in an attempt to keep it short. One 390 we looked at, the owner boasted, "And I've already had the $8,000 swim platform problem fixed!"

Most of the MS 390s we looked at already had the fix done, which was to remove the top of the swim platform, remove all the foam, put on some additional fiberglass where water intrusion is suspected, and some even provided a drain hole through the transom into the bilge (?!). Most repairs including the addition of 2 or 3 inspection ports in order to see what is going on in there, and pump out water occasionally if there was no drain hole to the bilge. The foam and a gabbard plug was the manufacturer's idea of a warranty repair for the defect... to prevent the [large] cavity from filling up with water.

The 2000 MS390 we ultimately ended up still with had all the original foam, and a gabbard plug that was removed every fall (as if that was a fix!). The original owner did not think the problem was a major problem and did not bother to fix it. The second owner = Same. I had heard all about this from LOTS of owners and surveyors, and I was no longer "horrified" about the defect. "It is a manageable defect."

Fortunately, I learned of a fiberglass guy who had fixed this problem "the right way" on 2 or 3 Mainship 390s in the past in nearby Rhode Island. For $4000, the guy would remove the top, clean out all the foam, remove the gabbard plug and fiberglass over it, do any additional F/G that was needed on the inside. There was a small yard fee for hauling it and all.

We wanted the fix done right for our "new" home / boat; we negotiated the work as part of our offer, and hours after closing on the boat our F/G guy went to work. He was done in a week, over 15 contractor bags of foam were removed, as he predicted. He put a nice piece of molding along the transom on top of the swim platform, and he also did a few other things for me. I did not want a drain hole into my bilge. So he did not do that. My plan was to use a Seaflo "Dry Bilge System" product which is designed to get the last inch of water out of any place on a boat, if needed.

Today, I know dozens of Mainship 390 owners, each have managed this in slightly different ways. None, including us, think this is a deal breaker for a boat that is very well built and well thought out in design in so many other respects. It is a very popular "Looper" boat, as we have learned on the Loop ourselves.

My advice is to get it fixed right. Pop the top, get the foam out, come up with your plan to evict any water that makes its way in there. It would be nice to find someone who has done the job before. If you happen to be near RI, I can help you with a guy's contact info! If you opt to simply live with the problem, you won't be alone... you'll be in the minority, but not alone. The Seaflow "Dry Bilge System" might help you either way. I've learned the pump is not very resilient to frost. But it does the job, and it isn't expensive to replace if it fails. It IS good at getting the last 1/4" of water (or less) out of that area (or any other.)

On this trip, I have talked with many owners of much more expensive boats, including Grand Banks, Sabre, etc. They all have stories of known manufacturer defects that have and how they manage them.

Click to expand...

I like what you did here and this is exactly what I plan to do if I find water in our new to us "99 MS 350. But.....why not the drain hole into the bilge? This seems to me to be a great way to monitor water intrusion in the future. You could visually see if any water was coming from the swim step cavity through the hole in the transom to the bilge plus it would be pumped out by the aft bilge pump. BTW, I use a small cheap shop vac on the boat for many things including getting the last bit of water out of any areas in the bilge. It has yet to fail but when it does I'll buy another one.

I am not familiar with the actual swim platform in question, or its geometry, but from your description I could imagine a half measure that involved drilling a 4", or 6" hole in each of the compartments in the swim step, in an area that would later get a larger hatch when you do the job right. Then from this 6" hole, attempt to tunnel down to the bottom of the swim step. That way there would be an open path water could drain out of the foam and collect in. You could put deck covers over the holes you cut, and periodically open them up, and shop vac any water that had accumulated out. Seems like if you were careful, the worst case is not that bad because even if it didn't work, it would not make fixing it right later any harder.

Shop Vac

Our platform may never have had the foam. There are two round 8” access ports on the platform, and a valve about 3/4 of the way up through the transom.

Several years ago we realized we had a serious leak. One of the trim tab screws penetrated the hill, had corroded away, leaving a pencil lead sized hole.

We hauled the next weekday and had the yard remove and glassover the trim tabs. We left the switches at the helms and the effect is about the same as when we had the tabs.

However, there is still water coming in. Every few months I take the shop vac and remove 30 - 100 gallons.

We are looong overdue for bottom paint. Before we haul I plan to remove the lid whilst in the slip and figure out where the intrusion is. May have to dust with chalk or something, but it needs to be fixed.

Will do before late fall and report back.

Jamie
Mainia, 2002 390 #350

blefever said:

I like what you did here and this is exactly what I plan to do if I find water in our new to us "99 MS 350. But.....why not the drain hole into the bilge? This seems to me to be a great way to monitor water intrusion in the future. You could visually see if any water was coming from the swim step cavity through the hole in the transom to the bilge plus it would be pumped out by the aft bilge pump. BTW, I use a small cheap shop vac on the boat for many things including getting the last bit of water out of any areas in the bilge. It has yet to fail but when it does I'll buy another one.

Click to expand...

Just my thing.

For me: intentionally providing a way for seawater to make its way into my bilge is a problem. There are way too many opportunities where that could have a catastrophic outcome. Say, I have to leave the boat without shore power on a mooring for a few weeks, batteries go dead pumping out the bilge. Backing into a slip, additional unseen damage is done to the swim platform, more water begins unknowingly flowing into bilge. The possible scenarios are endless. I don't even like pumping seawater into my hull for A/C, when I am not aboard! I am always checking those thru-hull fittings and hose connections at the other ends. My head's seawater seacock is always closed. We'll add fresh water from the sink as needed. Knowingly providing a way for seawater to unknowingly enter the bilge is simply a non-starter for me.

Just my thing.

Sorry, but you asked - fix it properly - this is no place for wire nuts. Take the top off, get the foam out (what were they thinking?) and do something to stop the leaks. Otherwise the science project you will get in there will be awful, not to mention stability concerns and every other complication of a leaky boat will arise. Do it correctly once. I would also need a bilge pump and an inspection hole in case it gets breached.

If you are fussed about hatches, put a roll of carpet runner on it. It’s kind on bare feet. We rolled ours up every time we retracted the ladder to get under way and replaced it every few years.

Somebody tried to put foam in aircraft floats once, they were completely impossible to repair because you couldn’t get in there plus the water came in under pressure and stayed. Fail.

What is the volume of water that can get in your transom? Remember that water weighs 10# per (real) gallon.

To those that have replied, some admitting they're not familiar with the setup of the Mainship 350/390 and some that simply don't, here are a few things to keep in mind.

1) It's not really a "swim Platfom". I believe they call is a 'bussel'. It is a hull extension that is bolted onto the original swim transom.

2) The extension is made in two pieces, like a hull and deck. The hull portion is bolted to the transom and glassed in. The deck is bolted, and caulked with a rub rail.

3) It is the deck of this extension which makes the 'swim platform'.

4) It is almost 3 feet deep filled with closed cell foam.

Try as you might, I've never seen a water intrusion issue resolved. The only solution is a water REMOVAL system.

That said..................

Shrew said:

To those that have replied, some admitting they're not familiar with the setup of the Mainship 350/390 and some that simply don't, here are a few things to keep in mind.

1) It's not really a "swim Platfom". I believe they call is a 'bussel'. It is a hull extension that is bolted onto the original swim transom.

2) The extension is made in two pieces, like a hull and deck. The hull portion is bolted to the transom and glassed in. The deck is bolted, and caulked with a rub rail.

3) It is the deck of this extension which makes the 'swim platform'.

4) It is almost 3 feet deep filled with closed cell foam.

Try as you might, I've never seen a water intrusion issue resolved. The only solution is a water REMOVAL system.

Click to expand...

Nicely said and a good observation. That said....where do you believe the water comes from? Trim tabs or deck lid joint or both? I have the recall paperwork from Mainship and they seem to focus on the trim tabs do to the fact that they say to locate the inspection ports right over the trim tab box. I have the same boat you do and have not yet addressed the issue but I don't think I have a problem........yet. The boat was out of the water a couple of months ago and I pulled the plug in the bottom of the "Buessel" About 3 or 4 ounces is all that came out.

Capt Ray said:

For me: intentionally providing a way for seawater to make its way into my bilge is a problem. There are way too many opportunities where that could have a catastrophic outcome. Say, I have to leave the boat without shore power on a mooring for a few weeks, batteries go dead pumping out the bilge. Backing into a slip, additional unseen damage is done to the swim platform, more water begins unknowingly flowing into bilge. The possible scenarios are endless. I don't even like pumping seawater into my hull for A/C, when I am not aboard! I am always checking those thru-hull fittings and hose connections at the other ends. My head's seawater seacock is always closed. We'll add fresh water from the sink as needed. Knowingly providing a way for seawater to unknowingly enter the bilge is simply a non-starter for me

Click to expand...

My thing, too

jclays said:

Sorry long winded title.
I am posting this in open forum rather than the Mainship forum because I am looking for broader ideas.
That said I know what the permanent fix is for the Mainship 350/390 swim platform taking on water and soaking the foam inside. Rather than tear the platform open, remove the foam reseal the platform and install hatches that I find ugly. I am looking at a dewatering solution that I can perform several times a year depending on the amount of water that actually seeps inside the swim platform.
I was thinking if I can drill/cut a hole in each compartment (3) large enough for a hose of sorts attached to a pump and pump out the water in each compartment on a regular basis. Maybe a vacuum type pump that could pull water from the foam after it removes any standing water. Then install a hole plug and every twice a year repeat the dewatering process. I am right now not interested in the permanent fix but rather just to de-water the compartment.
What say you
Thanks in advance
Jim

Click to expand...

If the boat is hauled for the winter as ours is the water freezes and thaws. only fix is to take out foan before the core in the platforn rots. I took out 1000lbs of water when finished

blefever said:

I like what you did here and this is exactly what I plan to do if I find water in our new to us "99 MS 350. But.....why not the drain hole into the bilge? This seems to me to be a great way to monitor water intrusion in the future. You could visually see if any water was coming from the swim step cavity through the hole in the transom to the bilge plus it would be pumped out by the aft bilge pump. BTW, I use a small cheap shop vac on the boat for many things including getting the last bit of water out of any areas in the bilge. It has yet to fail but when it does I'll buy another one.

Click to expand...

If you don't do the drain hole through the transom correctly your transom will get wet and essentially ruin the boat.

If anyone is interested in seeing a swimplatform dissected you can see it in the first 5 minutes of this video. The boat owner takes the top off and removes the foam. His solution was to resurface the inside and put a bilge pump in there. He also adds a stern thruster, underwater lights and extends the platform by 2 feet with an aluminum plate. Its a long video, but by just skipping through the first 5 minutes you can see how the original platform was constructed.

A significant source of water intrusion on the 350 and 390 is at the joint between swim platform deck and the hull extension or bustle. On many production hull deck joints, the parts just aren't sealed at all or sealed well, instead they caulk the top and bottom of the rub rail. On the 350 and 390, the forward edge of the rub rail has a gap between it and the hull and it serves as a scoop to force water inside of the rub rail and into any gap between deck and bustle.

It is a lot of work but if you remove the rub rail and the fasteners, you can clean up the two molded fiberglass members and seal them up with a good adhesive caulk. This will cut down on much of the water ingress. Filling in the scoop formed by the forward end of the rub rail helps a lot. On my father's 390, the foam was removed by a PO and access hatches added but no pump was installed. After resealing just one side of the rub rail in the process of replacing the port side rub rail (locking incident), the water inflow can be managed with a hand pump a couple times each a season. Water probably comes in through the trim tab fittings as well as the added deck hatches, as water pools on the top of the swim platform but it is much less ingress than before.

If you don't like the look of hatches on top, just cut the access hole you need and have it glassed back up when you are done removing the foam. With the foam removed a garboard drain or two on the bottom of the bustle would allow you to drain the platform when the boat is hauled. If the foam is wet, and it probably is, you aren't going to get the water out without removing the foam. I like the access hatches, and would consider it for trash storage (well sealed) on a long cruise.

Xsbank said:

Sorry, but you asked - fix it properly - this is no place for wire nuts. Take the top off, get the foam out (what were they thinking?) and do something to stop the leaks. Otherwise the science project you will get in there will be awful, not to mention stability concerns and every other complication of a leaky boat will arise. Do it correctly once. I would also need a bilge pump and an inspection hole in case it gets breached.

If you are fussed about hatches, put a roll of carpet runner on it. It’s kind on bare feet. We rolled ours up every time we retracted the ladder to get under way and replaced it every few years.

Somebody tried to put foam in aircraft floats once, they were completely impossible to repair because you couldn’t get in there plus the water came in under pressure and stayed. Fail.

What is the volume of water that can get in your transom? Remember that water weighs 10# per (real) gallon.

Click to expand...

What is a "real" gallon?