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Bow Sprit for Beneteau 25

Projects: Build the band using the boat as the mold; build foam landing strips for the tubes; cut the tubes at proper angle and laminate across the cut; dry-fit everything and glue with proset; laminate the tubes and foam to the band; build a step; build G10 end-cap with machined holes and stainless pin to transfer tack line loads directly to the bobstay; laminate end-cap to tubes; putty, sand, primer, and paint; install on boat with custom bobstay system
 



The bow before we removed all the hardware
We started by vacuum-bagging the band onto the bow section. We came up with some nifty tricks to nail down the centerline and not lose it during the rest of the building process.
Cold winter weather requires baking the part before we can pull it off the boat.
After pulling the band off the boat, we cut the tubes at the right angle and started the process of joining all three together. We cored and laminated the tubes across the cut to strengthen the bond to the band.




The plans called for foam landing strips to be built in order to laminate the tubes to the band.  Everything gets dry-fitted before gluing.
Finally, we used pro-set epoxy to glue the tubes,the foam strips, and the band. We left generous fillets in the edges to laminate the carbon onto in the next stage of construction.
Every lamination was vacuum-bagged. Here we bagged the "step", which prevents the tubes from bowing out under load.





We will make final trim lines once the part is on the boat.
There are so many complex angles and radiuses on this part that not vaccum bagging would have resulted in air spaces and having to use much more putty to fix all the imperfections.
Our target weight was 9.5 lbs. Right now the part is 8.90 lbs and we are almost done laminating. We still have to putty, primer, and paint.
The end of the sprit has a machined G10 plate that was glued into the tubes and then laminated over with carbon. In this pic the sprit has been puttied and sanded. 
The bow section required some  putty. We are ready to primer now. After shooting primer.
Despite using relatively little putty,  radiuses come out fairly even.






I sprayed glossy light gray on the tubes and stickered on the name of the boat Next we shot the entire sprit in glossy black paint. We will peel the stickers up after to reveal the name.
I had several sessions of puttying and primering to get rid of imperfections and pinholes.