Thanks to everyone for the replies to my prior questions about epoxy
and fiberglass (discounting the use of polyester). You help and
experience is appreciated.

I'm planning to build a dodger for my sailboat, still researching and
discovering..

After photographing hundreds of hard dodgers, and studying them
carefully, I know that hard angular corners will not look good on my
boat. I need to round the edges/corners to match the rest of the boat.

What techniques should I research for changing the hard corners where
two ply surfaces connect? How do I shape those round edges smoothly to
have a professional looking curve?

Plywood seems to be a good core for the large surfaces. I may use two
or three 1/4 ply layers glued with epoxy. 1/4 inch ply will allow some
curve to the sides and top, and having multiple layers will provide
strength. This is a 50 foot boat, so 1/2 to 3/4 inch thickness would
not look too flimsy, and the boat can accommodate the weight.

My question at this time is how do you make a smooth tidy round corner
where the sides and top meet, and where the sides and the front of the
dodger meet. It seems that connecting the ply large surfaces together
would add structural strength, but that would cause a hard angular
appearance.

Thanks for your input, (and please forgive my lack of experience).

-Koos.

Use a quarter round trim strip to form the corner, where you have a
radius on the outside, and a square corner inside, which you can trim
or fillet. For other than 90 degree corners, trim the strip on a
table saw. Use thin plywood and build up the edges to meet the trim
strip depth and accept screws holding it together.

Arrange to remove the plywood mold plug from the inside by covering
the outside with waxed paper. After you have built up sufficient
thickness of glass, drill out the screw heads and remove the screws to
remove the mold panels. Fill the screw holes.

I considered just glassing over the old canvas, for that slouch hatted
look.

Terry K

On Aug 23, 11:05 am, Terry K wrote:
Use a quarter round trim strip to form the corner, where you have a
radius on the outside, and a square corner inside, which you can trim
or fillet. For other than 90 degree corners, trim the strip on a
table saw. Use thin plywood and build up the edges to meet the trim
strip depth and accept screws holding it together.

Arrange to remove the plywood mold plug from the inside by covering
the outside with waxed paper. After you have built up sufficient
thickness of glass, drill out the screw heads and remove the screws to
remove the mold panels. Fill the screw holes.

I considered just glassing over the old canvas, for that slouch hatted
look.

Terry K

Thanks Terry, that is very helpful.

I think you are suggesting that I make rounded corners from molds, to
be added to the structure afterwards. So I would make the structure
using wood in the corners to provide strength, and then add the
rounded corners and finish them. that is my interpretation..

I might be able to use the existing cabin-house as a male mold to get
the same curve? Using wax paper and protecting the area with plastic,
I could perhaps use fiberglass and epoxy to form the corners for
adding to the dodger later. Let me know if you think this is a crazy/
unworkable idea.

Thanks for the ideas.

-Koos.

wrote:

What techniques should I research for changing the hard corners
where
two ply surfaces connect? How do I shape those round edges smoothly
to
have a professional looking curve?

Plywood seems to be a good core for the large surfaces. I may use
two
or three 1/4 ply layers glued with epoxy. 1/4 inch ply will allow
some
curve to the sides and top, and having multiple layers will provide
strength. This is a 50 foot boat, so 1/2 to 3/4 inch thickness would
not look too flimsy, and the boat can accommodate the weight.

You are going to end up making a male mold and then doing a classic
"one off" construction.

I definitely would NOT use plywood as a core material, but rather use
1/2" Divinycell foam.

Best guess is probably about $3/sq ft for full 4x8 sheets.

Probably get the job done with 2 sheets so estimate maybe $200 for
foam.

Foam can be cut into strips to go around corners, I've done it several
times.

You do realize that this will be at least a 2 year project and cost at
least $1K before you are done.

Lew

On Aug 23, 12:12 pm, "Lew Hodgett" wrote:
You are going to end up making a male mold and then doing a classic
"one off" construction.

I definitely would NOT use plywood as a core material, but rather use
1/2" Divinycell foam.

Best guess is probably about $3/sq ft for full 4x8 sheets.

Probably get the job done with 2 sheets so estimate maybe $200 for
foam.

Foam can be cut into strips to go around corners, I've done it several
times.

You do realize that this will be at least a 2 year project and cost at
least $1K before you are done.

Lew

Thanks Lew,

Thanks for the foam suggestion. Why not ply? Because it rots? Because
it's heavy? Other reasons?

I should explain that the sunbrella dodger/bimini/surround I have now
is ugly, too vertical and also it has aged. It would cost $2,000 to
$5,000 to fix it or to replace it (change the shape).

I'd like to make a full hard dodger and combined hard bimini to cover
the entire cockpit. Then add sunbrella sides and soft windows aft of
the dodger. I'd like to be able to open the center window of the
dodger, for ventilation. I may have a window in the ceiling (bimini)
to see the sails, but probably not. I will probably have brackets for
mounting solar panels, and may include a conduit for power cables.

To have a shipyard build this would be very expensive (double the
above numbers), and I'm not confident that I would like the result. So
I expect my project to be expensive, when it's all done.

I plan to make some form of disposable mock-up, to determine the
details. It should be the right height, it should allow visibility, it
should be aesthetically acceptable, it should allow crew to work the
lines and winches etc. Until I'm happy with this aspect, I won't begin
construction.

Yes it will take a long time, especially considering my other
projects.. I was hoping to get it done within a year though (probably
not)..

Thanks for your advice.

-Koos.

wrote:

Thanks for the foam suggestion. Why not ply? Because it rots?
Because
it's heavy? Other reasons?

Before I get into the details, one question.

Is this by chance a center cockpit boat?

Lew

On Aug 23, 1:15 pm, "Lew Hodgett" wrote:

Before I get into the details, one question.

Is this by chance a center cockpit boat?

Lew

Yes it is. A Gulfstar 50 center cockpit Ketch. They usually have an
ugly phone-booth style dodger and surround/windows. Something like
this one;
http://tinyurl.com/34bc4k

May I add a question? With the foam, should I plan to build a wood
frame to provide the structural strength? So the foam is attached to
the frame, rather than just fiberglassing the foam pieces to each
other?

Also, your website, any updates? I'm interested in your project. Your
help is appreciated - thanks!

-Koos.

wrote:

Yes it is. A Gulfstar 50 center cockpit Ketch. They usually have an
ugly phone-booth style dodger and surround/windows. Something like
this one;
http://tinyurl.com/34bc4k

AH HA, new game plan.

Look at the "roof" of the bimini/dodger of that G/S50..

Think, "How would I make that out of cored fiberglass and use roll up
side and front curtains?".

You simplify comstruction as well as end up with a place to "plant
your solar garden."

It is/was my game plan.

If that interests you, get back to me.

BTW, don't think of it as a telephone booth, think of it as a covered
patio.G


http://LewsSailBoat.googlepages.com/home


Lew

I must be missing something here. A dodger is just a roof. Why all the
epoxy and glass? I wouldn't use any glass and just use wood and epoxy
for sealing. You should be able to build it in place and wood is alot
easier to work with than glass. Either paint it or leave it natural.

Bob

On Aug 23, 11:03 am, wrote:
Thanks to everyone for the replies to my prior questions about epoxy
and fiberglass (discounting the use of polyester). You help and
experience is appreciated.

I'm planning to build a dodger for my sailboat, still researching and
discovering..

After photographing hundreds of hard dodgers, and studying them
carefully, I know that hard angular corners will not look good on my
boat. I need to round the edges/corners to match the rest of the boat.

What techniques should I research for changing the hard corners where
two ply surfaces connect? How do I shape those round edges smoothly to
have a professional looking curve?

Plywood seems to be a good core for the large surfaces. I may use two
or three 1/4 ply layers glued with epoxy. 1/4 inch ply will allow some
curve to the sides and top, and having multiple layers will provide
strength. This is a 50 foot boat, so 1/2 to 3/4 inch thickness would
not look too flimsy, and the boat can accommodate the weight.

My question at this time is how do you make a smooth tidy round corner
where the sides and top meet, and where the sides and the front of the
dodger meet. It seems that connecting the ply large surfaces together
would add structural strength, but that would cause a hard angular
appearance.

Thanks for your input, (and please forgive my lack of experience).

-Koos.

wrote:

I must be missing something here. A dodger is just a roof. Why all
the
epoxy and glass? I wouldn't use any glass and just use wood and
epoxy
for sealing. You should be able to build it in place and wood is
alot
easier to work with than glass. Either paint it or leave it natural.

This is going to be a large, say 12x12 rigid dinghy that will support
a solar panel farm.

Wood is heavy, wood will rot, and wood is weak when compared to a foam
core complete with knitted glass and epoxy skins.

The above structure would add a lot of weight high above the water
line if made of wood.

Just for reference, a 4x8x1/2 sheet of plywood weighs about 42#, while
a 4x8x3/4 sheet of Divinycell weighs about 16#-17#.

Lew