Installing a Larger Spinnaker Tube on Van Munster USA 8822

by Dave Burchfiel, USA 8822

I found it difficult to raise the spinnaker on my Van Munster due to the small tube size so I decided to put in a larger one. Another problem with the old tube was it was so thin it cracked several times causing the forward tank to leak and needed to be repaired.

                                                                   Before                                                                              After

I talked to Larry Tuttle and he said he wasn't sure how well his kit would fit a Van Munster.  I called OZ and decided to buy one of the new kits they make however after 9 months of calling and sending emails without response I decided to make one. Above are the pictures before I took a saw to the boat and then the finished product.  The original tube is tiny in comparison to the new one.

   
                                         Before                                                                                 After

Again the size change is substantial. It more than doubles the volume of the old launcher and it’s stronger.  It’s 2 ½ #’s heavier (5 ½ #’s vs. 3 #’s) so I’ll have to have the boat weighed and take out some of the 40#’s of lead I’m carrying.


Here’s where the biggest problem was.  The original tube (fore ground) which was narrow at the entrance to begin with got very small as it made the turn.  It was a little over 5 inches in diameter.  The new one behind it measures about 9 1/2” at its narrowest point and has a larger radius in the turn. To begin the project I cut out the old tube,  properly repaired a hole in the bow and then taped some bunk carpet to the inside of the bow which acted as a 1/4'” spacer.  I then covered it with plastic and laid up fiberglass to obtain an opening shape as large as possible. So I basically had a thin fiberglass skin lying about 3/16” from the hull at the bow.  This would give me the basic largest shape I could use for the new tube.  I then put a piece of glass across the top so it would hold its shape.  See below.

Except for the tube itself I used polyester resin with some extra catalyst so things would set up quickly and it’s much cheaper than epoxy.  I also used a hair dryer to further speed up the process.


Now I had to make a plug to be the exact size of the new tube.  Basically I figured I could make it out of almost anything as long as the shape was right.  I used a combination of 8” steel vent pipe.  $4.50 at Home Depot, some sheet metal I had lying around and some old Lumber.  Since the tube doesn’t exit the center of the boat it is by necessity slightly asymmetrical.   To help with the fitting and to get the angles right I actually built the plug around the old tube.  When the shape was close I covered the whole thing with 2 layers of 6oz. cloth. The plug at this point was rough to say the least.  A gallon of body filler and 10 pounds of dust from sanding, fitting and sanding again and the basic plug was ready.

The completed plug, sort of.


Since I was making the tube in 2 halves, upper and lower the plug would need parting flanges.  I used 2 layers of ½” foam insulation covered with packing tape to give me something to mold to. Once the flanges were set they needed to be sanded filled and faired and then 2 coats of resin were applied to the entire plug and sanded to 2000 grit.


The finished plug with mold release applied. I probably could have used this as a male mold but the fitting tolerances were tight so I was to make a female mold from the plug.


The mold is laid up on the plug.  Ribs were used so it would hold its shape when removed from the plug. I used the same foam weather stripping that I used to shape the parting flanges covered in mat for the ribs. The top half was done in the same manner after the bottom was removed from the plug.


The bottom half of the tube laid up in the mold.  It’s made with 2 layers of carbon twill since it easily forms around bends and West Epoxy.  I just used a wet layup and squeegeed out the excess.  The top was done in the same manner.


The two halves screwed together.  I fit the new tube in the boat.  It needed to be trimmed to the proper length.  I then removed it, separated the 2 halves and primed the inside with several coats of Awlgrip 454 white primer.  Wet sanded to 2000 and put the 2 halves together using epoxy thickened with colloidal silica and screws on the flanges.  The screws are there to keep the halves positioned while the epoxy sets.

   

The tube installed. The tube was epoxied in using carbon twill.  The areas of the bulkhead that had to be repaired /replaced were made using a single layer of carbon a layer of 1/8” core-cell a second layer of carbon a second layer of core-cell and a final carbon layer.  I made templates out of poster board before making the bulkhead pieces.  Everything was then faired and painted.