Thought for the day - fitting the fin

Yesterday was all about getting the fin box fitted. Alignment of the fin in exactly the right position with the design measurements and having it vertical is the most critical job on the boat. Get this wrong and the boat will be hard to balance and may sail higher on one tack that the other.


The boat in my jig is set up to be level on its water line, ie there is a horizontal line connection the bottom of the bow and bottom of the stern. The leading edge of the fin sits perpendicular to this line. Get the jig right and everything is easy. On the plan there are two measurements, one from the stern to the leading edge of the fin and then one from the tip of the bow to the bottom of the fin where it enters the bulb. Set these measurements and the fin leading edge should be perpendicular. I was less than a degree out.


To get the fin exactly vertical looking from the stern, I level the boat at the shroud point and use a level on the fin to make vertical and then use masking tape to secure it.


All the pictures are below and should show how it was done. The string in the picture is used to measure from the bow to the fin.


Tomorrow, I can fit the final pieces of the deck and the bulkhead.

The magic string measuring from the bow to the tip of the fin


Fitting the fin


Checking the fin is vertical

Had to cut a couple of hole to get the string straight from the bow to the fin

I initially glue and fillet the fin with 5 min epoxy and microspheres and then reinforce it with a layer of 124gm s glass

Levveling at the shroud point. I take the measurement just behind the foredeck

Measuring string taped to the bow

The slot cut out with a dermal and then carefully sanded

Bow reinforcement. It only needs to take tension

Fitting the fin box

41 views0 comments