Re: Double Bottom on Martha Jane.
-
Mark and Steve,
Thanks for the imput, lots of food for thought
there. I'll brainstorm it a bit more yet, but the pros seem to be
outweighing the cons at this stage. Wastage would not be so bad with
the offcuts, the leeboards and rudders on the revised plans have to
be built up to 2 inches and 1 & 1/2 inches rom memory.(only got them
yesterday) Being the cheapskate that I am, I thought at least on the
leeboards I'd have a full sheet for the outsides and offcuts of the
inch sheets cut to fill in the middle.
Compliments to Mr B by the way on those leeboards,
thought they were quite brilliant.
Col
-- Inbolger@egroups.com, Mark Albanese <marka@o...> wrote:
Mark and Steve,
Thanks for the imput, lots of food for thought
there. I'll brainstorm it a bit more yet, but the pros seem to be
outweighing the cons at this stage. Wastage would not be so bad with
the offcuts, the leeboards and rudders on the revised plans have to
be built up to 2 inches and 1 & 1/2 inches rom memory.(only got them
yesterday) Being the cheapskate that I am, I thought at least on the
leeboards I'd have a full sheet for the outsides and offcuts of the
inch sheets cut to fill in the middle.
Compliments to Mr B by the way on those leeboards,
thought they were quite brilliant.
Col
-- Inbolger@egroups.com, Mark Albanese <marka@o...> wrote:
> Mark Albanese wrote:
> >
> >
> > Col,
> >
> > When I promoted single sheets I was thinking of something
> > thinner than 1". But for you:
> >
> > 2. Good scarfs are always stronger than the wood.
> >
> > 1. From the study plan, I can see that the curve in MJ's
> > belly is very gentle. The worst is in that 6' section under
> > and just behind the tanks. The bottom's almost straight
> > apart from that. 1" sheets fulcrummed at the deepest part of
> > the hull would surely work the long way, if they were wide
> > enough. Since you have to lay them athwartships, right there
> > they might be a little too stiff.
> >
> > It would save A LOT of work, though, if you can get away
> > with it. This makes it sound more complicated than it will
> > probably be, but to get any needed extra leverage for the 4"
> > rise beyond the tanks, you could either fasten temporary
> > levers or make up an 8' x 8' sheet of ply. Patience and some
> > warm water might make all the difference.
> >
> > Why not spring for a sheet of cheap stuff to play around
> > with? Generations of builders could be in your debt.
> >
> > ( Another not quite so elegant idea is to use the 1" sheets
> > in the straighter parts of the bottom and only laminate with
> > thinner stuff between . )
> >
> > Whadaya think?
> >
> > Mark
> >
Mark Albanese wrote:
to take a curve, the advantage of double layered bottoms
might be to protect against the poor quality of cheaper
plywood. Sort of a way to distribute the voids.
Mark
>I had the thought that, apart from maybe being the only way
>
> Col,
>
> When I promoted single sheets I was thinking of something
> thinner than 1". But for you:
>
> 2. Good scarfs are always stronger than the wood.
>
> 1. From the study plan, I can see that the curve in MJ's
> belly is very gentle. The worst is in that 6' section under
> and just behind the tanks. The bottom's almost straight
> apart from that. 1" sheets fulcrummed at the deepest part of
> the hull would surely work the long way, if they were wide
> enough. Since you have to lay them athwartships, right there
> they might be a little too stiff.
>
> It would save A LOT of work, though, if you can get away
> with it. This makes it sound more complicated than it will
> probably be, but to get any needed extra leverage for the 4"
> rise beyond the tanks, you could either fasten temporary
> levers or make up an 8' x 8' sheet of ply. Patience and some
> warm water might make all the difference.
>
> Why not spring for a sheet of cheap stuff to play around
> with? Generations of builders could be in your debt.
>
> ( Another not quite so elegant idea is to use the 1" sheets
> in the straighter parts of the bottom and only laminate with
> thinner stuff between . )
>
> Whadaya think?
>
> Mark
>
>col_mooney@...wrote:
> >
> > Just a quick question that has been bugging me about double
> > bottoms, on boats such as Micro, Long Micro, Martha Jane etc. In the
> > earlier discussion about doubling the bottom ply someone asked "why
> > not just one thicker sheet?" I may have missed the reply if there
> > was one.
> > I'd planned to double sheet my MJ, as I figured the generous
> > offcuts would be useable elsewhere on the boat, which I figured was
> > one of Phils reasons. Then I thought I'd be clever and save time,
> > glue and maybe money by using one layer of inch thick. Should I or
> > should I not use 1 inch sheets to make the bottom? The only possible
> > drawbacks I can think of, which may or may not be valid, are:
> > 1. The 1" solid piece will not curve around to meet the sides,
> > 2. Traditional scarf joints are not suitable.(although on my
> > 16ft sailing dory with considerable rocker this method was used - 9ml
> > bottom - seems fine)
> >
to take a curve, the advantage of double layered bottoms
might be to protect against the poor quality of cheaper
plywood. Sort of a way to distribute the voids.
Mark
Col - When you use 1/2 inch instead of 1 inch - it's easier to get the curve
- and you will have overlapping seams - which means you won't be relying only
on your cloth for a water tight seal and you will have greater strength at
the joints and you will have more laminations. What scarfs by the way? There
are no scarfs on the bottom. The plywood joints are butted but offset from
the lower layer. Steve ( mj Landroval)
ps
my sponsons and new rudders will be finished and painted today. A good
feeling.
- and you will have overlapping seams - which means you won't be relying only
on your cloth for a water tight seal and you will have greater strength at
the joints and you will have more laminations. What scarfs by the way? There
are no scarfs on the bottom. The plywood joints are butted but offset from
the lower layer. Steve ( mj Landroval)
ps
my sponsons and new rudders will be finished and painted today. A good
feeling.
Col,
When I promoted single sheets I was thinking of something
thinner than 1". But for you:
2. Good scarfs are always stronger than the wood.
1. From the study plan, I can see that the curve in MJ's
belly is very gentle. The worst is in that 6' section under
and just behind the tanks. The bottom's almost straight
apart from that. 1" sheets fulcrummed at the deepest part of
the hull would surely work the long way, if they were wide
enough. Since you have to lay them athwartships, right there
they might be a little too stiff.
It would save A LOT of work, though, if you can get away
with it. This makes it sound more complicated than it will
probably be, but to get any needed extra leverage for the 4"
rise beyond the tanks, you could either fasten temporary
levers or make up an 8' x 8' sheet of ply. Patience and some
warm water might make all the difference.
Why not spring for a sheet of cheap stuff to play around
with? Generations of builders could be in your debt.
( Another not quite so elegant idea is to use the 1" sheets
in the straighter parts of the bottom and only laminate with
thinner stuff between . )
Whadaya think?
Mark
col_mooney@...wrote:
When I promoted single sheets I was thinking of something
thinner than 1". But for you:
2. Good scarfs are always stronger than the wood.
1. From the study plan, I can see that the curve in MJ's
belly is very gentle. The worst is in that 6' section under
and just behind the tanks. The bottom's almost straight
apart from that. 1" sheets fulcrummed at the deepest part of
the hull would surely work the long way, if they were wide
enough. Since you have to lay them athwartships, right there
they might be a little too stiff.
It would save A LOT of work, though, if you can get away
with it. This makes it sound more complicated than it will
probably be, but to get any needed extra leverage for the 4"
rise beyond the tanks, you could either fasten temporary
levers or make up an 8' x 8' sheet of ply. Patience and some
warm water might make all the difference.
Why not spring for a sheet of cheap stuff to play around
with? Generations of builders could be in your debt.
( Another not quite so elegant idea is to use the 1" sheets
in the straighter parts of the bottom and only laminate with
thinner stuff between . )
Whadaya think?
Mark
col_mooney@...wrote:
>
> Just a quick question that has been bugging me about double
> bottoms, on boats such as Micro, Long Micro, Martha Jane etc. In the
> earlier discussion about doubling the bottom ply someone asked "why
> not just one thicker sheet?" I may have missed the reply if there
> was one.
> I'd planned to double sheet my MJ, as I figured the generous
> offcuts would be useable elsewhere on the boat, which I figured was
> one of Phils reasons. Then I thought I'd be clever and save time,
> glue and maybe money by using one layer of inch thick. Should I or
> should I not use 1 inch sheets to make the bottom? The only possible
> drawbacks I can think of, which may or may not be valid, are:
> 1. The 1" solid piece will not curve around to meet the sides,
> 2. Traditional scarf joints are not suitable.(although on my
> 16ft sailing dory with considerable rocker this method was used - 9ml
> bottom - seems fine)
>
> Are there any other drawbacks I may have missed? Any imput to help
> me solve my dilemma would be appreciated.
>
> Regards,
> Col
>
> Bolger rules!!!
> - no cursing
> - stay on topic
> - use punctuation
> - add your comments at the TOP and SIGN your posts
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