Build a Sailboard

Building a Wide Style Board

4M - The Sailboard Thing

Jon's Boat

The following is a collection of notes from an exchange of emails concerning one construction project.

Here are the questions:

1)Was your board made by one block of styrofoam?
If not, then how many blocks did you use?
I suppose the difficult part must have been glueing the nose
which should have the 20 cm rocker!

2)Does your board have a stringer? Maybe two, so that the mast and fin boxes
can be put in the middle?

3)To the best of my knowledge, a woven glass fiber layer's width usually
does not exceed 80cm. Do you have succesive layers overlapping in the
middle? I'm thinking of using successive layers laminated on the left and on
the right rail, but I haven't figured out the stepping effect that might
happen where the edges of layers meet in terms of strenght.

4)How many layers of glass fiber did you use? Any sandich materials, carbon
fibers, kevlar etc?

5)Did you use vacuum bagging to make your board?

6)When did you put in the finbox, before or after laminating?

7)Did you use woodies? I haven't yet understood what good the are anyway...

8)Is there any special balance on the board which points out the location of
the mast track and the fin?
I'm worried that the boards nose might sink if I get the mast track way too
forward and perhaps my board won't have good upwind abilities if I put it
closer to the fin.

9)These damn footstrap inserts are too expensive. Is there any other
material I could use, like epoxy thickened with glass baloons or sand? I've
got some ideas, but I would like to hear what you chose to do.

Well, that should be it for now. I hope I will have more questions soon :-).
I'm sending you a picture of the outline and stringer of my board. What I
did was try to figure out the dimensions of a DROPS FL-13, which was about
280cm long and rearrange the dimensions, modifying them to meet my board
specs.
My board is to be about 90cm wide and 250cm long. I've already designed and
almost cut the stringer and the outline on a material which is something
like plywood (only much cheaper), so I'm getting ready for the blue styroam
cutting part of the job.
 Just have a look and tell me what you think :)!
>From my calculations, the mast track will be located at 110cm and the
finbox will be at about 10cm from the tail.
 I can only assume that this board will require very large sails, based on
its width, I wish to use it however with my 6.7. Should I start copying a
flapper race fin?

Thanks for your help, I appreciate it very much!
I look forward to finding out more about your own board building project,

Stelios

Stelios, I like the look of you board design.

Answers - as best I can!

1.    No, two main pieces. The join was towards the nose. I cut an angle
with the hot wire cutter so that the nose 'block' was angled up to match the
rocker. I also added side blocks to increase the width.

2.    No it doesn't have a stringer. I used Dow Chemicals Styrofoam FB of 32
Kg/m3 density. This is just tough enough to get away without having a
stringer if the board has lots of depth. NOT recommended for a low volume
wave board.

3.      Yes, the 'standard' width is 80cm. However SP Systems certainly do
wider cloths. I used 80 cm with the overlap along the centre line on the top
of the board and a wider cloth on the bottom as I didn't want to risk having
any step on the under side. SP Systems agent in Greece is :

         Neo Marine Ltd
         Costas Mimikopoulos
         30 1 412 0137
         30 1 411 2446
         Wneomarine@europlanet.com
         W110 Vass Pavlou Ave
         Piraeus
        18533
        Greece

4.    I used 210g cloth with three layers on top, but with some overlap on
the centre line, and two layers of the same 210g cloth on the underside. For
my wide style board I didn't use any exotic materials at all. If I was
really trying to make a light board I would use a very low density core and
then sandwich that with a hard foam shell of a few millimetres thickness
stuck using carbon and glass .

5.    I did use vacuum bagging but I wouldn't consider it essential. If you
don't then I do recommend using peel ply on top of the glass as it allows
you to get a good compacted layup. The peel ply is ripped of when you are
ready to undertake the finishing stages.

6.    I always put my boxes in before laminating. I fill the slot with foam
off-cuts and top this with plasticine. After laminating it is a simple task
to cut out the slot and pull out the filling. I use tuttle fin boxes which
are mounted into a block of high density foam.
http://www.fiberglasssupply.com/Product_Catalog/SurfSailcom/surfsailcom.html

7.    I don't and I haven't understood either!

8.    My board is just over 255 cm and 76 cm wide. Measuring from the centre
line at the rear of the board.

The trailing edge of the fin is 9 cm. The rear fixing on the rear footstraps
is 25 cm. The rear fixing on the front footstraps is 80 cm. The rear of the
mast box is 123 cm. The mast box is 25 cm long. The centre of the foot
straps measured from the centre line of the board are 12 cm rear and 20 cm
front (these are unfashionably close to the centre line).

The tail of my board is flat (zero rocker) for 140 cm. The rocker was drawn
such that the thickness of the board tapers evenly from tail to nose. The
tail is 14 cm deep the nose 3 cm.

9.    A few years back I bought a large supply of my favourite footstrap
plug as they were being discontinued. They are nylon with a brass threaded
insert. They are designed to be hammered into a 12mm hole drilled after the
board is finished. Unfortunately I'm now running low. Alternatives all
appear rather poor to me. As a cost saver I would consider using beech
blocks inserted prior to laminating. These would need to be drilled
carefully for the screw being used. Something like a block 25 mm X 50  mm X
100 mm at each end of a footstrap.

I sail my board mostly with a Curtis 52 cm fin and a Gun 8.8 m2 sail. I have
had it out in wild conditions using a Neil Pryde 6.8 whilst totally over
powered. It tends to get airborne very easily in these conditions! I have
very impressed by my 'standard' tail shape and conventional fin - such that
I haven't had any interest in exploring flapper tails and the like.

I hope that your project is progressing well.

Best wishes

Nick

I like square rails. fast and easy to build! Mine are square to the 140 cm
point i.e. as far as the rocker is flat. Then I start a gentle progressive
tuck towards a semi circular shape around the nose. The 'square' vertical
part extends just over half the depth of the board, about 6 cm. More around
the tail.

When sticking styrofoam together either use a weak contact adhesive like a
carpet spray adhesive, this can be hot wire cut and sanded or use an epoxy
patch smaller than the foam that will remain as your board. Be warned, it is
virtually impossible to get a smooth shape across an epoxy glue join.

10 cm depth should be plenty of depth with a stringerless board using
DOW FB 32kg/m3 foam, especially if you doom the top deck as this
will be inherently stiff.

I use sugar sprinkeld onto a flow coat, mask the area you want to apply non
slip to, brush on the epoxy and wait until it has almost lost its
stickiness - approx 60 minutes in UK temps (15°C). Then sprinkle the sugar. You want
it to dent the epoxy not sink right into it.

With the tuttle box I use you cut or route a hole right through the board
insert the box with the bottom flush mark the excess top of the box, remove
the box and cut and sand it to fit flush top and bottom. I usually reinforce
the area above the box with a plywood plate to spread the bolt loads.

Gybying is fun it does go round quite well if you have lots of commitment
and keep it fairly flat. If it goes wrong it usually jumps sideways and
heads off in a straight line. I have a 30 year old Land Rover with leaf
springs it has similar characteristics in a corner.....

Jon Howes has done some 3D modelling and interestingly favours wide tails.
Somewhere I have a note with the URL for a site with all NACA co-ordinates
and the like. If I can find it I'll pass it on and add it to the speed
sailing site.

My board goes upwind very well, probably helped a lot by the square rails.

Keep me posted with progress

have fun

Nick