Subject

Building a male mold for a bimini is very straight forward.

A basic 4x8 sheet of 3ply, 1/2" plywood is about 42 lbs.

Divinycell foam is about 6 lbs/ft3.

Trying to fabricate a bimini using plywood will end up being a top
heavy slug and totally change the sailing characterstics.

You simply don't want to go there.

Lew

Good advise Lew, thanks. Have you worked with this foam before? Trying to
figure out how it is to work with and the general methodology of working
with it (& maybe some of the pitfalls).

Glenn.

"Lew Hodgett" wrote in message
...
Subject

Building a male mold for a bimini is very straight forward.

A basic 4x8 sheet of 3ply, 1/2" plywood is about 42 lbs.

Divinycell foam is about 6 lbs/ft3.

Trying to fabricate a bimini using plywood will end up being a top
heavy slug and totally change the sailing characterstics.

You simply don't want to go there.

Lew

"Glenn (s/v Seawing)" wrote in
message news:UW_Ki.8439$x%6.7141@pd7urf2no...
Good advise Lew, thanks. Have you worked with this foam before?

Built a 55 ft Bruce Roberts double head sail ketch using 1" Airex foam
for the hull and 3/4" Divinycell for the deck.

It is a very mature construction technique.

Lew

Glenn (s/v Seawing) wrote:

Good advise Lew, thanks. Have you worked with this foam before? Trying to
figure out how it is to work with and the general methodology of working
with it (& maybe some of the pitfalls).

Glenn.


I have.
It's a bit more challenging than plywood for one off coring.
But it would be the way I'd go if I were going to do this.
It's a weight issue.

For all the ins and outs may I refer you to the amateur built aircraft
industry - composite moldless construction as developed by Burt Rutan.

There is quite a bit of prior work to study there - and besides, you are
not worried about the wings folding so it's nowhere near as critical.


I recently made a pair of bunk shelves for my boat.
It's a Catalina Capri 18 - pretty small inside - although is seems big
enough outside.

The shelves are urethane foam cored with woven fabric skins. And West
resin - since that was what I had handy.

I used 5 ounce BID (BI Directional) glass (cuz that's what I had handy)
with 4 or 5 layers to get a good solid surface. Besides, the cores were
only about 3/16" thick, hence the heavy skins.

Wish I had taken pictures as I went along - but as usual I was too busy
wetting and squeeging.

They came out ok though. Haven't managed to paint them yet because I
took them out to the boat for installation fit - and they have been
there ever since...


For what you want to do I think I'd recommend something between 1/2 and
1 inch thick foam for the cores. I'd also make a plywood form to set
the desired curvature - and probably vacuum bag the skins.

Figure the bottom side could have lighter skins because (usually) nobody
will be walking on the bottom surface.

Look at what they call "units" in boat building rather than using woven
glass for something like this. (Cloth would be way expensive compared
to the boat unit approach). Units (as I understand it) are two (or
more?) layers of dissimilar materials - chopped strand matt and woven
roving or woven matt and woven cloth fabric.

I'd really like to buy Roger Long a cold beer and get all this straight
from the sea horse's mouth. All my experience is aircraft work - which
is quite a bit lighter stuff.


You may not absolutely need the vacuum bagging on a panel this size, but
if you've done it before you would know why you'd want to go to the
trouble and expense. (Better bonding to the core material - and a lot
easier surface finishing)

But it could be done as a straight forward hand lay up quite
successfully.

For a first time project this is really a bit big.

Building an airplane, one usually starts with a rudder and fin.
Small pieces to learn the techniques.

Then advance to the bigger and more critical structures.

I'd kind of like to do a project like you are discussing as the next
step before laying up an entire hull and deck.
'Specially if someone else is footing the bill


For what its worth, Glenn.


Richard Lamb



A few Marine Links:

http://boatdesign.net/articles/boatbuilding.shtml
http://boatdesign.net/articles/foam-core/index.htm
http://www.marinecomposites.com/ = excellent info!
http://microship.com/resources/micro-trimaran.html


Aircraft links:

http://www.maddyhome.com/canardpages/main (everybody)
http://www.maddyhome.com/canardpages...Dembs/Ch14.htm
http://www.ez.org/resource.htm

While I didn't build a hard dodger myself, I had one built by a very good
craftsman in Ft. Lauderdale. He took the existing bimini stainless and had
it welded in place so that it had the exact same form as the cloth one. He
used a 1" honeycomb material for the coring and overlaid it with 1/8"
fiberglass sheet on the top and on the bottom. The whole thing was faired
and them Awlgripped.

Everyone who has seen it has asked where I had it made as it's by far
better than anything available commercially, such as a WaveStopper. I will
point out that he said that he would never build another one! :-)

Here's a link to a photo of it:

http://www.geoffschultz.org/Ebay/hard_dodger.jpg


-- Geoff
www.GeoffSchultz.org

"Geoff Schultz" wrote in message
.. .
While I didn't build a hard dodger myself, I had one built by a very good
craftsman in Ft. Lauderdale. He took the existing bimini stainless and
had
it welded in place so that it had the exact same form as the cloth one.
He
used a 1" honeycomb material for the coring and overlaid it with 1/8"
fiberglass sheet on the top and on the bottom. The whole thing was faired
and them Awlgripped.

Everyone who has seen it has asked where I had it made as it's by far
better than anything available commercially, such as a WaveStopper. I
will
point out that he said that he would never build another one! :-)

Here's a link to a photo of it:

http://www.geoffschultz.org/Ebay/hard_dodger.jpg


-- Geoff
www.GeoffSchultz.org

The bimini looks very nice.
What is the canvas top behind it.
I have not seen all of the sailboat.
Where is the dodger?

--Denis

wrote in
:


"Geoff Schultz" wrote in message
.. .
While I didn't build a hard dodger myself, I had one built by a very
good craftsman in Ft. Lauderdale. He took the existing bimini
stainless and had
it welded in place so that it had the exact same form as the cloth
one. He
used a 1" honeycomb material for the coring and overlaid it with 1/8"
fiberglass sheet on the top and on the bottom. The whole thing was
faired and them Awlgripped.

Everyone who has seen it has asked where I had it made as it's by far
better than anything available commercially, such as a WaveStopper.
I will
point out that he said that he would never build another one! :-)

Here's a link to a photo of it:

http://www.geoffschultz.org/Ebay/hard_dodger.jpg


-- Geoff
www.GeoffSchultz.org

The bimini looks very nice.
What is the canvas top behind it.
I have not seen all of the sailboat.
Where is the dodger?

--Denis

The canvas shown in http://www.geoffschultz.org/Ebay/hard_dodger.jpg is the
bimini without the tightening straps attached. This photo shows the hard
dodger before the Strataglass windows were attached to the tracks.

Here's another photo showing the bimini taut and the Strataglass installed.

http://www.geoffschultz.org/Ebay/canvas.jpg


-- Geoff
www.GeoffSchultz.org

"Geoff Schultz" wrote in message
.. .
wrote in
:


"Geoff Schultz" wrote in message
.. .
While I didn't build a hard dodger myself, I had one built by a very
good craftsman in Ft. Lauderdale. He took the existing bimini
stainless and had
it welded in place so that it had the exact same form as the cloth
one. He
used a 1" honeycomb material for the coring and overlaid it with 1/8"
fiberglass sheet on the top and on the bottom. The whole thing was
faired and them Awlgripped.

Everyone who has seen it has asked where I had it made as it's by far
better than anything available commercially, such as a WaveStopper.
I will
point out that he said that he would never build another one! :-)

Here's a link to a photo of it:

http://www.geoffschultz.org/Ebay/hard_dodger.jpg


-- Geoff
www.GeoffSchultz.org

The bimini looks very nice.
What is the canvas top behind it.
I have not seen all of the sailboat.
Where is the dodger?

--Denis

The canvas shown in http://www.geoffschultz.org/Ebay/hard_dodger.jpg is
the
bimini without the tightening straps attached. This photo shows the hard
dodger before the Strataglass windows were attached to the tracks.

Here's another photo showing the bimini taut and the Strataglass
installed.

http://www.geoffschultz.org/Ebay/canvas.jpg


-- Geoff
www.GeoffSchultz.org

Nice, I like the color its the same as my canvas bimini and dodger.

On Sep 28, 9:56 am, Geoff Schultz wrote:
wrote :







"Geoff Schultz" wrote in message
. ..
While I didn't build a hard dodger myself, I had one built by a very
good craftsman in Ft. Lauderdale. He took the existing bimini
stainless and had
it welded in place so that it had the exact same form as the cloth
one. He
used a 1" honeycomb material for the coring and overlaid it with 1/8"
fiberglass sheet on the top and on the bottom. The whole thing was
faired and them Awlgripped.

Everyone who has seen it has asked where I had it made as it's by far
better than anything available commercially, such as a WaveStopper.
I will
point out that he said that he would never build another one! :-)

Here's a link to a photo of it:

http://www.geoffschultz.org/Ebay/hard_dodger.jpg

-- Geoff
www.GeoffSchultz.org

The bimini looks very nice.
What is the canvas top behind it.
I have not seen all of the sailboat.
Where is the dodger?

--Denis

The canvas shown inhttp://www.geoffschultz.org/Ebay/hard_dodger.jpgis the
bimini without the tightening straps attached. This photo shows the hard
dodger before the Strataglass windows were attached to the tracks.

Here's another photo showing the bimini taut and the Strataglass installed.

http://www.geoffschultz.org/Ebay/canvas.jpg

-- Geoffwww.GeoffSchultz.org- Hide quoted text -

- Show quoted text -

Nice Boat Geoff, are you ex-Navy? ie-Blue Jacket.

Joe

Geoff Schultz wrote:
While I didn't build a hard dodger myself, I had one built by a very good
craftsman in Ft. Lauderdale. He took the existing bimini stainless and had
it welded in place so that it had the exact same form as the cloth one. He
used a 1" honeycomb material for the coring and overlaid it with 1/8"
fiberglass sheet on the top and on the bottom. The whole thing was faired
and them Awlgripped.

Everyone who has seen it has asked where I had it made as it's by far
better than anything available commercially, such as a WaveStopper. I will
point out that he said that he would never build another one! :-)

Here's a link to a photo of it:

http://www.geoffschultz.org/Ebay/hard_dodger.jpg


-- Geoff
www.GeoffSchultz.org

Nice work!

But I can see why he wouldn't want to do it again.
It was truly a LOT of work.

Really looks appropriate on that boat too.

Richard