Primo Longboards: The other half of our shop

My sons are into longboard skateboarding and have launched a business.

They are carbon fiber molded decks.  We fabricate them alongside our boat projects.
Here are some photos:

Sup Plug: Step #6

Gel-coat overcoat.
After extensive sanding of the first layer of gel-coat, the plug is ready for the next layer.
With each layer, the number of issues (divots, surface blemishes etc.) are fewer.
It the following photos you can see areas that we added fairing on top of the first layer of gel-coat.
Once today's coat is added, the problems will be down to a handful.
I expect we will have one more pass.

Today's coat is a grey to contrast with the blue under-layer.

SUP Plug: Step #5 Gel-Coat

The SUP's plug is getting close to the uniform surface we are after.  But from experience we know there are problems that are hard to detect.  One thing that really helps is to spray on a layer of gel-coat.

By giving the surface a uniform color and material, the eye has a much better chance of spotting problems.

With this first layer of gel-coat, we will add a tint color.  Pure white is just too hard to see differences in.    

We also added a wax sanding aid to the gel-coat.  This allows the surface to cure hard so it is easier to sand.

After this layer hardens, we will continue sanding.  What else.

Here is white gel-coat in spay cup and a concentrated
blue tint color we add.

Here are the cup gun parts.

Mixed, assembled and ready to spray.

SUP Plug: Step #4: rounding the rail edge

To achieve a uniform rail edge we do a few different operations.   The initial plywood bend has to be a uniform bend.  Once this is accomplished the next step is to use a router with a radius bit to cut the sharp edge off the ply.  I used a 1/2 inch radius with a bering guide.
As the fairing progresses on the side wall, we roll a palm sander over this edge.  The ply is harder than the fairing material and it slowly brings the rail side wall into conformity.
Once the rail starts to look fair, we then move to this step:  Applying fairing material with a curved spreader.
Just a cheap plastic spreader will work.

We bend it and evenly follow the rail edge with the material.  This fills in voids and gives us a skim coat to hit with additional sanding with a sponge.
The whole process takes a lot of sanding.  No way around it.

And more fairing...

After several passes with sanding between layers of fairing, the bow was getting close.  But alas, I sanded through to the foam.  I've struck foam!  No major deal.  I scraped out the offending soft spot and filled with Bondo.

The side rails are getting close.  It is to the point were the variations are not visible to the eye.  But if  you run your hand along the rail, you can feel subtle high spots and depressions.
When we feel these areas, we mark them add a spot fairing and next will move to long board sanding.
To this point we have been using a palm sander and a course grit sanding sponge.

Sanded through to foam.

Filled cavity, ready to sand again.

Side rail.

SUP Plug fairing: Step #3

The new Sea State board we are molding is in the first stages of fairing.  The substructure, built of wood is as close to fair as possible.  This is helpful.  It allows us to keep the fairing materials we will add thin and get to the finish sanding stages sooner.  If there are underlying rough spots in the plug's structure, you can spend a great deal of time fixing it.  It pays to go slow and not create problems that have to be dealt with later.

Today we are giving the entire plug a skim coat of fairing material.  Later today it will get a sanding and an additional fairing coat.  After that is sanded we will decide if additional passes are needed.  Once this process is completed, it will be time to move to spaying gel-coat.  Gel-coat bonds to the plug and provides a surface that can be sanded and buffed to a high gloss.

These two photos show the bow of the SUP before and
after a bit of fairing.

The dimensions of the board are:

12' length

32" max width

5" thick

The estimated volume will be about 230 liters.  This will be a stable board for novice riders up to 275 pounds.

Here is an overview of the bottom of the SUP's plug..

SUP Plug forming: Step #2

 After the bow is pulled together, the hull bottom naturally forms a nice gentle v shape.
So now after the shape is secured, we have the heights or thickness of the board established.  The next thing to do is to set the sheer line or top edge of the entire deck surface.
I do this by ripping some 1/4 inch strips of wood (poplar).  I then mark out from the hull bottom 1 inch around the edge of the hull.

I do taper in to "0" at the bow and stern.  Next I shoot in the poplar strips to these markings.  This edge gives us something to fair to and hopefully keep the shape of the sides fair.

Next I fill in the void with foam.  I've used bondo and wood before, but foam is fast and it is only a base for further fairing.

Here you can see the poplar strip at the bottom edge of the sanded foam.

A couple of passes with great stuff, let it firm up then sand it down.

These two photos show the foam before and after disk sanding to the chine and shear line.

 Next I mark the center line with a string to make sure we are straight.  On this board I wanted a detail at the centerline to provide a little thickness for strength.  It will not be a skeg, just a slight rounded v.  The internal deck supports made of carbon fiber tube will rest on this centerline.
To form this, first we start with a furring strip.

The bow will have a pronounced v section and we form this by adding a vertical piece of wood. 

After the epoxy holding it sets, we mark a nice fair transition  and plane it down.

Then we sand it below the eventual
final surface.

Here foam is shot in to conserve
fairing compound.

Next we will start adding many passes of
fairing compound.

Shaping the next SUP in our line: Step #1

This weekend we started the process of forming a plug to make a mold to make out next line of SUPs.

The plan was to make some improvements that would allow us to make a hull that is more rigid, lighter and a little more graceful.

The new hull form is that of a flat water touring hull.  This is a displacement hull. This means a long form, low rocker and a water cutting bow. SUPs that are used in surf become planning hulls and benefit from rocker and being as short as practical.  All SUPs that are not being used this way (95 + %) are displacement hulls whether they are designed this way or not.

Our new board started out with these concepts in mind and this sketch:

From this start we began to loft the shape onto ply.
We have worked out a process to get to the plug.
Here it is...

We first get a ply material.  Of course, the plug never gets anywhere near water, so almost any ply will work.  In the past we have used masonite, this time we are using OSB.

We use battens to draw on a half profile.  This is one side of the board up to the centerline.
We use the machine edge of the ply for the center because it is reliably straight.

Once this is cut we use a hand planer to smooth the outer profile.  Then we use this shape to cut out it's other half.  These two halves are then affixed to the molding surface.

Because the length of the board is longer than standard sheet goods, we have to sister together the parts.  We do this by adding a ply piece on the underside with glue and screws.  This makes a stiff spot in the bendable ply but if it is in near the middle of the board this is not a problem and will be sanded and faired away.

This is the lap joint.

The next thing we do is to make a surface which mimics the shape of the eventual deck of the SUP.
We do this by bending an oversized piece of ply on saw horses.  The extra width provides a place for the flange of the mold.  The plug is formed right up to this plane and when the parts come out of the mold they have this same curved shape that will accept the deck.  Here some photos:

This is the sistered together half board profile.  It is  11 feet  9 inches.
Once the fairing is complete, the board will grow to an even 12 feet.

Here is the deck molding surface.  We introduced some rocker into this plane for fun and beauty.  The half shape is being affixed with specific heights and with a taper.

The thickness of the board is determined by this height.  We have set the maximum thickness of this SUP at 5 inches.

This shows the two halves set on the centerline.
A bit of material was removed on both sides in the rear.
They are screwed down flush at the tail and nowhere else yet.

When the bow is pulled together, this introduces a
little pucker which gives the hull a 'v' profile.
A sistered board underneath holds it together.
Then shims and screws are used to support this
shape.

Sailing Canoe re-varnish

The sailing canoe is stored on it's stand upside down and under tarps. this keeps it well protected from the elements but varnish doesn't last forever.  I checked on it and noticed some slight peeling so before the cold weather takes hold I figured now it the time to re-varnish.
I used 120 grit paper and gave it a complete sanding.  Then we sprayed on a a spar varnish thinned with naptha.  We used a semi-gloss formulation.  We will give it a couple days (or the winter) to dry then a light re-sand and re-spray.

After spray.

After sanding.

Band Saw guide

The big Silver Manufacturing Co. band saw we are slowly rehabilitating is getting some love.  We disassembled  the original blade guide.  It is at the end of a robust arm held by the upper part of the saw's casting.  It has a simple hand knob to set the guide height.  It is of a heavy enough guage to actually work.
The original guide is a simple design.  Where modern saws have bearing guides, this one has pieces of brass.  We may move to bearings, but first we will try using the unit as it was designed.
The fist at the end of the arm has adjustable sides and these were set with countersunk pieces of brass.
We had leftover brass from the skiff's cutwater so these were an easy replacement.
Here are photos of the saw, arm and guide.  The guide is a large two piece cast iron item.  In the photos the saw looks smaller than it is.  The guide is as large as a softball.
The next step before launch will be the fabrication and installation of guards and a safety switch.

Blade Guide with new brass liners. 

32 inch Silver band saw.

Guide fist stripped of guide brass, knobs etc.

Guide height adjusting knob.