On our boat Odin there's a hatch on the bathing platform which
currently lets water in (to the inside of the bathing platform). This
isn't disastrous in any way because the bathing platform was added by
the previous owner and thus its 'inside' is outside the hull of the
boat proper. However it is rather annoying and (as we discovered
recently) a *lot* of water in the bathing platform does actually upset
the trim of the boat slightly.

So I'm thinking of the best way to seal the hatch. The difficulty is
that it's not a proper hatch with any sort of rim, it's just a flat
plate bolted down onto the surface of the bathing platform. There is
a slight recess in the bathing platform, presumably with the intention
of making the whole thing flat (i.e. the recess is 4mm or so and the
plate is 4mm thick).

As I said the plate is (about) 4mm thick and the bathing platform
'body' is also 4mm thick. The plate is 500mm square and there are 8mm
bolts all the way round at about 75mm intervals.

My thought is to get a sheet of neoprene or similar that's 500mm
square and stick it to the bottom of the plate, make holes for the
bolts and hope it will seal. I'm thinking of 3mm thick.

The question is whether a full sheet of neoprene is necessary. Would
I get away with a strip (say 25mm wide) with joins at the corners, can
one seal joins like that satisfactorily? Or is there some other sort
of sealing strip that might be appropriate?

Any/all ideas would be most welcome.


--
Chris Green
·

Chris Green wrote:
On our boat Odin there's a hatch on the bathing platform which
currently lets water in (to the inside of the bathing platform). This
isn't disastrous in any way because the bathing platform was added by
the previous owner and thus its 'inside' is outside the hull of the
boat proper. However it is rather annoying and (as we discovered
recently) a *lot* of water in the bathing platform does actually upset
the trim of the boat slightly.

So I'm thinking of the best way to seal the hatch. The difficulty is
that it's not a proper hatch with any sort of rim, it's just a flat
plate bolted down onto the surface of the bathing platform. There is
a slight recess in the bathing platform, presumably with the intention
of making the whole thing flat (i.e. the recess is 4mm or so and the
plate is 4mm thick).

As I said the plate is (about) 4mm thick and the bathing platform
'body' is also 4mm thick. The plate is 500mm square and there are 8mm
bolts all the way round at about 75mm intervals.

My thought is to get a sheet of neoprene or similar that's 500mm
square and stick it to the bottom of the plate, make holes for the
bolts and hope it will seal. I'm thinking of 3mm thick.

The question is whether a full sheet of neoprene is necessary. Would
I get away with a strip (say 25mm wide) with joins at the corners, can
one seal joins like that satisfactorily? Or is there some other sort
of sealing strip that might be appropriate?

Any/all ideas would be most welcome.


How about laying down a thick continuous bead of neutral cure silicone
on the deck portion of the seal, grease the mating surface of the plate
and fit the plate but don't tighten the nuts much just enough to squeeze
out a little sealant. Clean up excess inside and out. set aside a blob
of the excess so you can tell when it had fully gone off (neutral cure
is often slower than the common acetic acid stuff). Remove the hatch,
clean off any grease and re fit tightening down the nuts this time.

On 04-Dec-16 3:35 PM, Chris Green wrote:
On our boat Odin there's a hatch on the bathing platform which
currently lets water in (to the inside of the bathing platform). This
isn't disastrous in any way because the bathing platform was added by
the previous owner and thus its 'inside' is outside the hull of the
boat proper. However it is rather annoying and (as we discovered
recently) a *lot* of water in the bathing platform does actually upset
the trim of the boat slightly.

So I'm thinking of the best way to seal the hatch. The difficulty is
that it's not a proper hatch with any sort of rim, it's just a flat
plate bolted down onto the surface of the bathing platform. There is
a slight recess in the bathing platform, presumably with the intention
of making the whole thing flat (i.e. the recess is 4mm or so and the
plate is 4mm thick).

As I said the plate is (about) 4mm thick and the bathing platform
'body' is also 4mm thick. The plate is 500mm square and there are 8mm
bolts all the way round at about 75mm intervals.

My thought is to get a sheet of neoprene or similar that's 500mm
square and stick it to the bottom of the plate, make holes for the
bolts and hope it will seal. I'm thinking of 3mm thick.

The question is whether a full sheet of neoprene is necessary. Would
I get away with a strip (say 25mm wide) with joins at the corners, can
one seal joins like that satisfactorily? Or is there some other sort
of sealing strip that might be appropriate?

Any/all ideas would be most welcome.



If it is an entirely separate structure, does it really need to be
watertight? If you drilled a few 4" diameter holes in the bottom, would
it affect the boat in any way?

--
--

Colin Bignell

Nightjar wrote:
On 04-Dec-16 3:35 PM, Chris Green wrote:
On our boat Odin there's a hatch on the bathing platform which
currently lets water in (to the inside of the bathing platform). This
isn't disastrous in any way because the bathing platform was added by
the previous owner and thus its 'inside' is outside the hull of the
boat proper. However it is rather annoying and (as we discovered
recently) a *lot* of water in the bathing platform does actually upset
the trim of the boat slightly.

So I'm thinking of the best way to seal the hatch. The difficulty is
that it's not a proper hatch with any sort of rim, it's just a flat
plate bolted down onto the surface of the bathing platform. There is
a slight recess in the bathing platform, presumably with the intention
of making the whole thing flat (i.e. the recess is 4mm or so and the
plate is 4mm thick).

As I said the plate is (about) 4mm thick and the bathing platform
'body' is also 4mm thick. The plate is 500mm square and there are 8mm
bolts all the way round at about 75mm intervals.

My thought is to get a sheet of neoprene or similar that's 500mm
square and stick it to the bottom of the plate, make holes for the
bolts and hope it will seal. I'm thinking of 3mm thick.

The question is whether a full sheet of neoprene is necessary. Would
I get away with a strip (say 25mm wide) with joins at the corners, can
one seal joins like that satisfactorily? Or is there some other sort
of sealing strip that might be appropriate?

Any/all ideas would be most welcome.



If it is an entirely separate structure, does it really need to be
watertight? If you drilled a few 4" diameter holes in the bottom, would
it affect the boat in any way?

Well no, except that the back end of the boat would sit a couple of
inches lower in the water. As I said it doesn't *matter* if it's got
water in it but I'd prefer that it doesn't.

--
Chris Green
·

On 12/4/2016 5:19 PM, Bob Minchin wrote:
Chris Green wrote:
On our boat Odin there's a hatch on the bathing platform which
currently lets water in (to the inside of the bathing platform). This
isn't disastrous in any way because the bathing platform was added by
the previous owner and thus its 'inside' is outside the hull of the
boat proper. However it is rather annoying and (as we discovered
recently) a *lot* of water in the bathing platform does actually upset
the trim of the boat slightly.

So I'm thinking of the best way to seal the hatch. The difficulty is
that it's not a proper hatch with any sort of rim, it's just a flat
plate bolted down onto the surface of the bathing platform. There is
a slight recess in the bathing platform, presumably with the intention
of making the whole thing flat (i.e. the recess is 4mm or so and the
plate is 4mm thick).

As I said the plate is (about) 4mm thick and the bathing platform
'body' is also 4mm thick. The plate is 500mm square and there are 8mm
bolts all the way round at about 75mm intervals.

My thought is to get a sheet of neoprene or similar that's 500mm
square and stick it to the bottom of the plate, make holes for the
bolts and hope it will seal. I'm thinking of 3mm thick.

The question is whether a full sheet of neoprene is necessary. Would
I get away with a strip (say 25mm wide) with joins at the corners, can
one seal joins like that satisfactorily? Or is there some other sort
of sealing strip that might be appropriate?

Any/all ideas would be most welcome.


How about laying down a thick continuous bead of neutral cure silicone
on the deck portion of the seal, grease the mating surface of the plate
and fit the plate but don't tighten the nuts much just enough to squeeze
out a little sealant. Clean up excess inside and out. set aside a blob
of the excess so you can tell when it had fully gone off (neutral cure
is often slower than the common acetic acid stuff). Remove the hatch,
clean off any grease and re fit tightening down the nuts this time.

Or wrap the plate in a couple of layers of cling film, or kitchen foil,
or greaseproof paper.

I'm a bit confused why the hatch exists in the first place. if this
structure is hollow why did they not put the sheet of whatever its made of
over the whole platform?
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Bob Minchin" wrote in message
news
Chris Green wrote:
On our boat Odin there's a hatch on the bathing platform which
currently lets water in (to the inside of the bathing platform). This
isn't disastrous in any way because the bathing platform was added by
the previous owner and thus its 'inside' is outside the hull of the
boat proper. However it is rather annoying and (as we discovered
recently) a *lot* of water in the bathing platform does actually upset
the trim of the boat slightly.

So I'm thinking of the best way to seal the hatch. The difficulty is
that it's not a proper hatch with any sort of rim, it's just a flat
plate bolted down onto the surface of the bathing platform. There is
a slight recess in the bathing platform, presumably with the intention
of making the whole thing flat (i.e. the recess is 4mm or so and the
plate is 4mm thick).

As I said the plate is (about) 4mm thick and the bathing platform
'body' is also 4mm thick. The plate is 500mm square and there are 8mm
bolts all the way round at about 75mm intervals.

My thought is to get a sheet of neoprene or similar that's 500mm
square and stick it to the bottom of the plate, make holes for the
bolts and hope it will seal. I'm thinking of 3mm thick.

The question is whether a full sheet of neoprene is necessary. Would
I get away with a strip (say 25mm wide) with joins at the corners, can
one seal joins like that satisfactorily? Or is there some other sort
of sealing strip that might be appropriate?

Any/all ideas would be most welcome.


How about laying down a thick continuous bead of neutral cure silicone on
the deck portion of the seal, grease the mating surface of the plate and
fit the plate but don't tighten the nuts much just enough to squeeze out a
little sealant. Clean up excess inside and out. set aside a blob of the
excess so you can tell when it had fully gone off (neutral cure is often
slower than the common acetic acid stuff). Remove the hatch, clean off any
grease and re fit tightening down the nuts this time.

In message , Chris Green
writes
My thought is to get a sheet of neoprene or similar that's 500mm square
and stick it to the bottom of the plate, make holes for the bolts and
hope it will seal. I'm thinking of 3mm thick.

The question is whether a full sheet of neoprene is necessary. Would I
get away with a strip (say 25mm wide) with joins at the corners, can
one seal joins like that satisfactorily? Or is there some other sort
of sealing strip that might be appropriate?

Our boat has a full-width cabin (ie no side decks) and we have guard
rail stanchions mounted on sort of inverted L-shaped plates made from
scrapyard stainless steel. These are bolted through.

I used the strip stuff sold by Aldi as garage wall car door protection
between the plates and deck, and it seems to have lasted and stopped
leaks through the bolt holes. I don't see why it should not compress
enough to seal at the joints, especially if they were not exactly at the
corners and with perhaps a bit of gunge.

--
Bill

Brian Gaff wrote:
I'm a bit confused why the hatch exists in the first place. if this
structure is hollow why did they not put the sheet of whatever its made of
over the whole platform?

It's about 3 metres by 1 metre so a sheet that big would be rather
clumsy and, if made of 4mm steel, rather heavy too I suspect.

--
Chris Green
·

Bill wrote:
In message , Chris Green
writes
My thought is to get a sheet of neoprene or similar that's 500mm square
and stick it to the bottom of the plate, make holes for the bolts and
hope it will seal. I'm thinking of 3mm thick.

The question is whether a full sheet of neoprene is necessary. Would I
get away with a strip (say 25mm wide) with joins at the corners, can
one seal joins like that satisfactorily? Or is there some other sort
of sealing strip that might be appropriate?

Our boat has a full-width cabin (ie no side decks) and we have guard
rail stanchions mounted on sort of inverted L-shaped plates made from
scrapyard stainless steel. These are bolted through.

I used the strip stuff sold by Aldi as garage wall car door protection
between the plates and deck, and it seems to have lasted and stopped
leaks through the bolt holes. I don't see why it should not compress
enough to seal at the joints, especially if they were not exactly at the
corners and with perhaps a bit of gunge.

OK, thanks, that sounds a possibility.

--
Chris Green
·