The fin tool is pretty easy to use. The only trick is to take your time and make sure everything lines up as prefectly as possible.

This can be difficult if you use epoxy that cures very quickly. I usually use something in the 15-30 minute range. That should provide enough time. A five minute cure time may be a bit fast, especially on a warm day (speeds up cure time).

First, make sure the fin took is on a level surface. Position the body tube so that the top fin slot faces up and the bottom one faces down. These fin slots should line up perfectly. Next, tack down the first fin by setting it upright into the top fin slot. You can use 15 minute epoxy, or similar, to tack down fins.

Now use a wooden board and stand it upright, in front of (and against) the fin tool. Make sure the board (or similar) has a perfect 90 degree angle. Move the board in front of the fin and make sure the fin is perfectly lined up with the board. Adjust the fin as needed until it lines up.

This shows a close-up. As you can see, the board and fin line up. The fin tool is on a level surface, the body tube is positioned properly, and the board has a 90 degree angle. Due to this, the fin will be installed correctly when it all lines up.

Once the epoxy cures, flip over the body tube so that the first fin faces down. Use the board again to make sure it still lines up with the fin (when it is pointing down). Insert the second fin in the top fin slot and tack it in place.

Just as we did for the first fin, we use to board to check alignment. Both fins and the board should all line up perfectly.

Here's a closer view of the two fins lining up. This will ensure the second fin is also installed correctly.

And here's a view from a different angle to help show how the setup works.

Once the epoxy on the second fin cures, move the bottom tube so that the fins stick out sideways. Measure the distance between the fin and the top of the fin tool for each fin. These must be equal for the fins to be level with the fin tool. Once the first two fins are level, install the 3rd fin in the top fin slot. This is done exactly as we did for the first fin. If you have to adjust it a little, make sure you don't move the body tube around too much. I always check to make sure the first two fins are still level once the third lines up with the board.

Finally, the last fin is installed. This is done the same way the second fin was installed. Once all four fins are tacked down and the epoxy cures, you can create epoxy fin fillets to secure the fins in place. For this, I prefer to use West System epoxy with colloidal silica mixed in.

Previous : Making the fin tool