swim platform replacement

[tooldev]

Hi all,
I have a 2002 Mainship 390. I like the boat but the swim platform is waterlogged in the core. one of the suggested fixes was to replace the swim platform with a standard having support struts as opposed to a fully enclosed "Tub". this would change the length of the hull.
but at the same time, there appears to be a lot of problems with water-intrusion and wet cores.

has anybody ever switched the swim platform to a conventional one?
I would appreciate any input.

Thanks
Peter

 

[Keysdisease]

Hello Peter,

The "original" model 350 did not have the bustle (technical term for the hull extension / swim platform) and squatted so badly Mainship felt the boat needed the additional flotation aft and so added the bustle.

There are as many opinions as 350/390 owners about what's the "right" fix, and the one almost universal agreement seems to be that while it's not a particularly good thing to have all that waterlogged foam in the bustle, it really causes no real harm either structurally or performance wise.

The factory fix (there was a recall at one time) was to dig out all the old foam. I know of some boats that left the platform empty, replaced the foam, only dug out a hole to the bottom and installed a pump, opened a limber hole to the main bilge through the transom, and several other "fixes." Several filled in the trim tab pockets considering them useless and a source of water intrusion.

I would not replace the bustle with a conventional swim platform for several reasons. One being it's probably more expensive and labor intensive than any other "fix" and will exaggerate the squatting noted originally. I think the simplest fix is to install 2 inspection ports and dig out the foam straight down until you hit bottom. Then either install a bilge pump and bring the hose and wires through a hole you will need to cut in the transom between the bustle and the bilge, or let water collect and manually pump it out as it accumulates.

Or, you could just enjoy your boat

Hi all,
I have a 2002 Mainship 390. I like the boat but the swim platform is waterlogged in the core. one of the suggested fixes was to replace the swim platform with a standard having support struts as opposed to a fully enclosed "Tub". this would change the length of the hull.
but at the same time, there appears to be a lot of problems with water-intrusion and wet cores.

has anybody ever switched the swim platform to a conventional one?
I would appreciate any input.

Thanks
Peter

 

[tooldev]

Thank you for your response,
swim platform modification was applied to my boat.
there is no foam and i have a drain plug and inspection ports.
my problem is that there is moisture in the glass, and according to the fiberglass repair guy needs to be Re-cored.
he called me today, saying that the re-coring is so extensive that he recommends the other style swim platform.
I totally agree with your assumption and guess that i need to have it re-cored.
I am not sure, but i think this fiberglass has been wet for many years and i am not sure if its even a big problem.

 

[Keysdisease]

Not too sure that much of the bustle is cored, all Mainships were solid glass below the waterline and only cored above the waterline. I can't imagine the bustle being any different.

Moisture in the fiberglass itself was a concern years ago about blisters, and any decent Marine Surveyor will take moisture readings. They really don't mean squat regarding structure, but are only an indication of potential or existing blister problems.

I believe this is an important observation:

"I am not sure, but i think this fiberglass has been wet for many years and i am not sure if its even a big problem."

If you're really concerned the next time you're hauled out maybe contact a surveyor and ask about checking moisture content. For a price a good surveyor will give you a straight answer about any real concerns.

 

[DavidM]

If the bottom of the bustle is solid fiberglass like the main hull and only the top is cored like the deck on the main hull, then unless the top is flexing too much when you stand on it, I would leave it alone.


Surveyors can identify moisture in coring, long, long, long before it becomes a structural problem and 99.99% of the time it never does.


I say fuggitaboutit.


David

 

[Jeff F]

Agree with advice offered. Even if the coring is wet, so what? Any damage is limited to the bustle - it can't metastasize into the boat proper and all indications are that the bustle section will continue to do its intended function. Let it ride and revisit once a year.

I've sort of been aware of this issue through Mainship forums and came across one of these boats out of the water recently. I wonder if the molds are still kicking around? Seems like any small manufacturer could easily churn out bolt-on replacements.

 

[Comodave]

The coring is most probably just in the deck as previously mentioned. If it is only the deck coring is bad, it isnt a horrible problem to fix. Cut the top off, dig out the wet core, replace the core and reglass the deck back on. If you are not real good at fiberglass and painting, make the cut on the top and fair it as best you can then paint with Kiwigrip which will cover a lot of minor defects in the finish work. I would not remove the bustle. Mainship went to a lot of trouble to come up with this fix to the squatting problem.

 

[DHeckrotte]

I recall seeing several versions of this 'bustle'. One was an obvious paste-on, one was an extension of the hull. I've heard of several fixes for the paste-on since they were apparently prone to leaking. I think these were also the basis of the 350/390 otherwise identical boats. If I had a soggy foam-filled paste-on; I think I'd holesaw a couple 6" holes, dig out the foam, find and fix the leak(s), and use a couple Beckson deck lids to keep an eye on 'new' water and be able to pump it dry. No need to carry the extra weight; no need to have your eventual buyer tell you to fix it or walk away.



We liked these boats well enough to look at several but settled on our FuHwa.

 

[tooldev]

Thank you all for your Input, everything makes a lot of sense.
we measured a high moisture content in the bustle so i decided to get it fixed properly.
it may not be absolutely necessary but i feel better having the piece of mind.
besides, the design did not make too much sense.
there are 3 chambers inside the bustle, separated by stringers. the middle one is not accessible. the partitions have drain holes about 1-2 " above the bottom, which means there is always water trapped in the middle chamber.
the shop recommended we install new dividers with drain holes right at the bottom and add a bilge pump.
This is and excellent boat and we like it a lot, that bustle was a constant source of worry since i don't know what we get away with. in addition, the coring on the wall where it joins the boat was also wet. over time, the bolts holding this to be boat will loosen off.
If i keep the boat, i know its sound and if i sell it i feel good knowing the next buyer gets a good boat.
The shop doing the work will provide me with photos which i will gladly share.
Thanks again and happy boating