Refurbishing SC20

[Kevin Keller]

I am in the middle of refurbishing my boat. I was originally concerned about some wrinkles I saw on the upper side of the hull forward of the front beam. Along with some cracks in my beam I decided to take the boat home and do some repairs.

You might find these of interest. I have learned a lot about the construction of the boat and from the pictures you might also.

I have owned the boat for about a year and a half. I think it is an '82.

I started by grinding the paint and gel coat from the forward hull being careful not to remove fiberglass. I guess a previous owner had decided to put some fiberglass tape over the seams between the two halves. The wrinkles I had seen looked to be caused by the fiberglass being too thin around the seam. I assume that maybe when they sanded the seams prior to taping they took too much away.

There was some damage to the inner core were the wrinkles in the seam met the core. So I ground away the foam and filled it in with a mixture of epoxy and aerosil. After it hardened I put several layers of fiberglass over it and vacuum bagged it.

Vacuum bagging is actually very easy. I bought a used air conditioner from Craigslist for $20 and removed the pump. I recommend the largest pump you can get. If you have large leaks sometimes it is hard to find the leaks without enough airflow. I picked up some peel ply and breather material from a local fiberglass store. There is plenty of information on the internet on how to do the bagging.

[Kevin Keller]

More photos.

[Kevin Keller]

Now I flipped the boat over and started on the bottom. I wanted to put a new layer of tape over the bottom seam. I found some tears in the existing fiberglass and found some of the foam was still wet despite being out of the water for 8 months. I think I finally found the elusive leak.

There were quite a few dings I had to repair.

[Kevin Keller]

This is the other hull which needed some repairs. I noticed on both hulls that the bulkhead underneath the forward beams had separated from the inboard hull. I was able to repair the aft side through the access port. I was hoping the front side was ok but I happened to look through the bolt holes and saw the same thing. So I ended up cutting holes in the bottom to repair this damage.

The first thing I did was make a patch to put back in. I just layed down some plastic over the area to be cut and put 3 layers of 6 oz fiberglass.

I also cut two more holes in the bottom to reinforce the transom and I also added two foot straps to each hull. To back up the foot strap screws I shaped some plastic blocks and epoxied them in. I also put a strip of fiberglass over the blocks to help hold them in if I take the screws out.

[Kevin Keller]

After repairing the bulkhead I had to close the hole again.

I took the patch I made, trimmed it and put a wire through it.

[Kevin Keller]

Now I went to the transom to reinforce it.

[Kevin Keller]

Here I reinforced the transom. It does not look pretty but it is hard to work blind. I think it will help a lot though.

I added 3 layers of fiberglass to the lower part of the transom where the majority of the damage would occur from a hit to the rudder.

[Kevin Keller]

These are a couple of shots looking through the middle hole I cut to add the foot strap backing blocks.

By the way, I cut the holes on the bottom instead of the top because I felt that the fiberglass repair would do a little better under tension rather than compression.

I need to finish up this hull and bring the other hull back in to do the same repairs to the transom and the forward bulkhead.

More photos to follow. I look forward to any questions or comments.

[jjd78]

excellent work..... thank goodness i don't have to do that much work.... looking forward to the final outcome!!!!

cheers
jason

[Kevin Keller]

So am I!!

[Matt Haberman]

Kevin,

Quite the project you have taken on. Looks like you have a good handle on the repairs.

For whats its worth, I think your boat is more like a 1980-81 vintage. Looking at how the hull was put together tells me it came from the original 20 mold, which was only used for a year or so before it was replaced with a new mold which made the transoms and decks integral with the rest of the hull. By the time 1982 rolled around, Boston Whaler had taken over production and the original mold had been retired.

[george]

Looks great, and thanks for posting the pictures. This kind of job is in the near future for me on a 1980 SC20 I just picked up, and having those internal pictures are so helpful.

I will probably drop you a note in a month or so to get some more advice/info on some of the work you did.

Curious what you are planning on doing to finish the hulls, painting? With what, and are you going to do it yourself?

[Kevin Keller]

George,

Drop me a note anytime.

I am going to paint it myself. I have a HVLP turbine sprayer I will use. I have seen another catamaran rolled with Awlgrip though that looked awesome.

I am going to use Concept paint. I think it is made by PPG and I have painted my car and a jetski with it. I will start with a sealer primer coat. The original resin was polyester with gelcoat and some other unkown coats of paint. This sealer should negate any compatability issues, I hope. Next coat will be a filler primer, which should fill in any sanding scratches. Then I will put the top coat, a single stage (no clear coat).

These are all PPG products and it is easy to touch up and blend in real nice. I am gone half the time with my job so it might be a while before I am finished.

As I said the boat was made using polyester resin. So if you want you can use poylester resin again, it is cheaper. However epoxy is supposed to give a better bond. Also if you do not know the history of past repairs and what they used for resin I would go with epoxy. You can use epoxy resin over polyester but it is not recommended to use polyester over epoxy. I did not know if epoxy had been used on previous repairs. Something else to note, gelcoat, which I am pretty sure your boat has, cannot be applied over epoxy. So with these reasons, Matt's recommendation, and knowing I will paint it, I chose epoxy resin.

There is one other resin available polyvinyl. I think it can be used over epoxy or polyester resin.

Hope that helps. I have a ton more advice when you are ready.

Kevin

[Kevin Keller]

I noticed along the rim, the layer of fiberglass from the transom had separated from the rim. So I took a die grinder and removed it down to the polyester glue. If you look close you can see it all cracked along the bottom. I will clean it up and fillet it with some epoxy and aerosil. Then lay some fiberglass along the edge.

I think some water had been coming through the crack.

[randy33allen]

I recently purchased a 1982 Boston Whaler 17 Supercat. It has spidering in the fiberglass at the transom and the gel coat has flaked a little at the seam. Your renovation and pictures are a great help. How hard is it to do another layer of gel coat?