Skeg Repair

[Don52]

My friend and customer Steve has owned this 27’ boat for 25 years. Counting the boat that he had before this one, he has owned power boats for 35 years. Steve’s strategy is to leave the boat in storage and trailer it to the lake every time that he uses it. For the first time in 35 years, he forgot to raise the lower unit of the inboard/outboard drive when he pulled the boat out of water. As a result, he wore about ¾” from the bottom of the skeg. My task was to replace the worn off piece of the skeg. Steve felt that the bottom of the skeg helps to protect the two counter rotating stainless-steel propellers, which cost ~ $2,500. If the skeg hits something on the bottom it will likely cause the lower unit of the inboard/outboard drive to rise and avoid damaging the propellers. (At least that is the theory.)

1. Steve’s 27' boat-1


2. Steve's 27' boat-2


3. Worn down skeg


I know that it is low tech, but I just used a cardstock pattern to define the shape of the replacement piece for the skeg.

4. Cardstock pattern


Ryan Jones from the Miller Welds forum queued me in regarding the availability of replacement skegs. It turns out the skegs are airfoil in shape with the center being about twice as thick and the leading and trailing ends. In our case the center was .220” and the ends were .100”. I compromised by using 3/16” stock. If you want to be geometrically pure, you would have to cut the bottom off of the replacement skeg tip. Another option is to use 1/4” stock and do a lot of grinding if you want to blend it to the existing skeg.

5. Replacement skeg tip

[Don52]

6. Cutting replacement piece


I like to use a copper backup plate to protect the back of the weld from oxidation during welding.

7. Copper backup plate


I used garbage cans and a small shade to protect me from wind. The part that I was welding was far enough from the gear box that I didn’t worry about burning up the grease. I also took my time welding it, so it would cool off between welds.

8. Me TIG welding skeg


9. Close up of me welding


10. Skeg welded

[Don52]

When you grind aluminum make sure that you use a wheel designed for Aluminum, like the one shown below, otherwise the wheel will load up.

11. Aluminum grinding wheel


I like to back gouge to ensure that I remove all of the oxidation from the back of the weld.

12. Back gouging skeg


In the evening here in Michigan it is currently in the low 50’s, so I used my shop lights to help the paint to dry.

13. Using 2x 500-watt lights to dry paint


14. All done and painted-1


15. All done and painted-2


-Don

[ryanjones2150]

Your customer is lucky he didn’t grind off part of his prop too!

CAD to me means cardboard aided drafting, so your card stock is as high tech as my shop gets!

Good repair.

[Don52]

Your customer is lucky he didn’t grind off part of his prop too!

The props are in excellent shape considering that they are the original ones. The only problem he ever had was that the seal wore a groove in the journal of the prop and leaked. He had the journal spray ceramic coated and ground and the props have worked ever since.

CAD to me means cardboard aided drafting, so your card stock is as high tech as my shop gets!

LOL

Good repair.

Thanks

-Don