One of the mainstays of our business is installing teak decks and covering boards on high end sportfishing yachts. Here in Jupiter we are close by many custom builders and also are a destination/jumping off location for boats coming down from the north for the winter.
Currently we are fabricating and installing a teak deck and covering board/coaming for a new 60' Hatteras sportfisher.We have developed a style of covering board/coaming that we call the Palm Beach style. Traditionally very wide teak boards are used for covering boards.These boards are very expensive and are only available with lots of flat grain in the board. Flat grain boards are inherently unstable and very prone to checks and splits, especially around penetrations such as rod holders and hawse pipes.This is sometimes dealt with by fiberglassing the bottom side of the covering board before it is installed. Our belief is that we are epoxying the teak to a fiberglass panel on the boat . A teak to fiberglass epoxy glue joint is a teak to fiberglass epoxy glue joint.
Hatteras sportfishers have a very pronounced sheer in both the vertical and fore and aft directions. We have a technique that was developed specifically to address both the large curvature and to minimize checks and splits. We purchase rough slabs of teak that are from the center of plain sawn logs that are very straight grained and as clear from all natural irregularities as possible. Then we resaw the boards to bookmatch them and then resaw them in the other direction to a width appropriate for the curve of the transom.
The first step is to make accurate templates of the shapes required. This helps us pick out boards that we can use and avoid knots, lightning marks, bug holes and other blemishes.
Then its off to the lumber dealer to sort through piles of teak slabs looking for just the right ones for this project.This is fun because you see many beautiful boards, yet a bit stressful because these boards are pricey and they all have the potential to have bad surprises inside
Once we have the boards and have laid them out its time for cutting. Our shops primary large band saw is this Italian Centauro 800.It has a 5hp motor and it is so far the smoothest cutting band saw I've ever used. It looks like many similar sheet metal saws but is almost a ton of cast iron. The controls are easy and the guides are tough to get aligned just right but every time we shut it down we are saying ,wow what a great saw.
Here we have assembled our bending knees according to the templates plus just a little bit more for spring back.Springback is pretty much a guess, a composite of strake width, strake thickness, curvature, and the number of strakes in the assembly.
Before we can glue the stakes together we plane the edges to get a very tight fitting glue joint. It is a very satisfying thing to take a single shaving off the edge of a board 16' long. After the edges are planed we then sand the very carefully with a small block with 80 grit to give some tooth for better adhesion.
Here the strakes are prepared and on the bending form ready for gluing.
Here you can see the side covering boards, one set glued and clamped, and the other ready for gluing.
Now we have glued and clamped the aft board. The next step will be to form the coamings . That will be in our next post.
No comments:
Post a Comment