Stress cracks in bow

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A

Asa Colson

Has anyone had stress cracks on the bow of their Hunter 31. Our surveyor found them just forward the head near the water line. He recommended supporting the bow under the holding tank to reduce oil cannning and the cause of the stress cracks. Has anyone had to make this modification with their boat?
 
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David

Bow stress cracks

I don't know the cause but I have noticed the condition on other 31's. Have you actually noticed oil canning while underway?
 
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Steve Larson

Been there, done that

I had them on my H31 and took corrective action. Search the archives for the posts under the caption "FOLLOW UP FOR STEVE".
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Different area though.

Steve: When you did your repairs, were they in the bow area? What year is your boat? The reason I am asking is because one of my fellow sailors in our marina had/has this problem. There were strengthers inside the hull in the v-berth. I was wondering if this was only a problem on early production models.
 
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Steve Larson

Same area, same problem

Mine is a 1985 H31. The cracks were more severe on the starboard side and could be seen through the bottom paint. The cracks on the port side could only be seen when I sanded through the barrier coat. They were longitudinal cracks which ran parallel along the length of the bow starting about a foot from the bow to about the doorway under the v-berth. I sanded thru the gelcoat in these areas and the sanded area was about 14 inches by 4 foot. I have my depth transducer right in front of the doorway and I went around this from the starboard side but not the port side. The repair was easier than I thought it would be and turned out great. Using the West System epoxies I added three layers of matting fabric to the outside and three to the inside. The matting to the inside was of the large weave variety (west marine)laid so that the weave would reinforce the bow area and the outside was of the smaller variety laid along the bias of the curvature. It seems as though there are some other boats out there that have taken a pounding and have been stressed in this area. I would suggest that if you have an H31 you consider beefing up the fiberglass in the area from as far as you can reach under the holding tank to just aft of the little doorway under the v-berth. It really is not a bad job as long as you invest in a mask with suitable filters. That doorway sure is small though.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Steve L!

The h'31 that I saw with cracks where above the water line about 8-12" below the toe rail. Sounds like you did your repairs from the inside. This boat will need a gel coat patch regardless of where the patch is made.
 
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Steve Larson

Steve D

All of the cracking that I have heard about has been similar to mine which was below the waterline. My repair was to make a sandwich of the original fiberglass after removing the gelcoat. On the exterior I used the West System Epoxy, three layers of matting with Interlux 1000 (gelcoat replacement) followed with Interlux 2000 barrier coat and Petit Trinidad SR bottom paint. I can't imagine how you would get cracks in the hull where you have described them as this area is not one that is put into a flexing action by the normal stresses you encounter with the water.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Steve L (continued).

Steve: I agree. Don't know how this could have happened. He bought the boat like that. I think it was used very hard. If it was not on both sides like this, I'd think that they had hit something.
 
A

Asa Colson

More info

I have not made the repairs yet. We plan to have the repairs made in the stress cracks when 6the boat is pulled this winter. I am not supporting the bow until I hear from the forum. The cracks are verticle and appear to be right on a bow bulkhead. They are approximately 6 inches high. My plan is to build up support in the area below the holding tank. I plan to put in an additional plywood bulkhead supporting it with expandable foam.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Be careful how you do the repair.

Asa: Be very careful how you do this repair. If it looks patched you WILL have problems if/when you go to sell the boat. A surveyor will look a lot closer at an obvious repair. They will know that something is being covered up. Fiberglass is amazing in it's strength. Laying up a few layers of glass and resin should not be a very expensive repair. They roll on some paint and it will look like new. I would think that if you remove the wood bulkhead under the v-berth there will be adequate access to the area. If you are real concerned about strength you could use some Kevlar cloth instead of fiberglass mat. While you are in there, you should also clean out the holding tank and inspect it for any problems too. It would be a good time to clean-up and repair the entire area. I do not think you want to go back there any time soon. Good luck. Take some pictures and post them in the Photo Forum. They make excellent reference.
 
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JErry

2 cents worth

Asa, For what it's worth (my opinions are 2 cents retail - cheaper if bought in bulk !!) IF the cracks are vertical AND IF they at on a bulkhead what you probably have is what's called a 'hard spot'. Basically the hull is against the bulkhead and cannot flex AT ALL. Therefore what happens is almost a hinge like action at the edge of the bulkhead resulting in vertical cracks. Solution is the cut the bulkhead so that is it not against the hull, put a cushion of closed cell foam between the bulkhead and hull and retab with cloth and resin. Can be a bit of an involved job depending on access to the edge of the bulkhead. Good luck with it. Jerry
 
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Asa Colson

2 cents may be worth thousands

I find your 2 cents very interesting. The problem is exactly as you describe it. I had not considered removing bulkhead as a solution to my problem. Your solution makes sense to me. Does anyone else have any opinions on the this type of solution? Would it work?
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Worth looking at!

Asa: Jerrys insite on your problem makes some sense. I would think that you may be able to get a small saw (hacksaw blade or such) between the bulkhead and the hull and remove any excess material. It would seem that you may be able to see this spot. I must assume that the bulkhead would be resting upon the hull all the time. When the boat is sailing there is twisting in the structure, but the bulkhead is rigid. This may be causing the spot. The worse case senario would be to remove the bulkhead and plane it down. This would be a lot of work but not impossible by any means. They did this on my H'31 when they replaced the compression post and replaced the bulkhead between the head and the main salon.
 
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