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  #1  
Old 04-04-2010
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Hull Deflection

Cape Dory 25, Vanderwide picture by davidm203 - Photobucket

This is the bottom of a Cape Dory 25. It looks to me like the cradle pad is deflecting the hull a noticeable amount.

Two things I didn't like.
1. Deflection of hull.
2. Full liner inside so I couldn't see the inside of the hull.
3. Really, Really messy bottom.
4. Taping the bottom it seems like the hull is very thin. I can distort it by hand just by pressing it with my palm. Maybe this is because it is only a 25' er and the hull is just thin.

I'm getting to the point were I have looked at enough boats and done enough repairs so I can see problems now.
What I would like it to know if they are serious problems. There always seems to be some thing that can't be seen or some test that is too expensive to do to find out if the something is a big problem or a little problem.

What do you think about this one?
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Old 04-04-2010
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the deflection is less important to me than the fact that it appears to be an unpadded pad. was there any cracking or crazing around the pad? I couldn't tell from the pic.
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Old 04-04-2010
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It does look like it is deflected a bit by the cradle pad. I don't think you should be able to deflect it with your hand on a 25' boat, especially a Cape Dory quality of boat. I really don't think deflection should be common on the bottom of any boat larger than maybe 20'.
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Old 04-04-2010
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Quote:
Originally Posted by bljones View Post
the deflection is less important to me than the fact that it appears to be an unpadded pad. was there any cracking or crazing around the pad? I couldn't tell from the pic.
P4040017.jpg picture by davidm203 - Photobucket

Cracking or crazing. You have to be kidding. The bottom was so rough you could hide loose change in the cracks.

It might be nothing or there may be something that should be tabbed in on the inside that came loose. It really annoys me that I can't figure out what it is.
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Old 04-04-2010
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Quote:
Originally Posted by mitiempo View Post
It does look like it is deflected a bit by the cradle pad. I don't think you should be able to deflect it with your hand on a 25' boat, especially a Cape Dory quality of boat. I really don't think deflection should be common on the bottom of any boat larger than maybe 20'.
That's what I thought. I've pounded on the flat spot between the turn of the bilge and the turn of the keel with the palm of my hand on a lot of boats and all I can remember is that it was like pounding on concrete.

I'll pick a quite day at the marina and compare with some other boats about the same size. Maybe it's the difference between 25 and 30+ feet.
I was surprised and that compared with the deflection from the pad makes me wonder.
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Feel free to correct me, but I see it like this;
Boat should be supported by keel when on the hard, with the pads only stabilizing the boat. Yes ?
How many stands are/were supporting the hull ?
Were the supports over tightened so that they are trying to lift the hull and not just stabilize it ?
If the supports have been over tightened to the point of damage then is it the yards problem or .....?
With a full liner....how does one access the damage ?
The pressure on the hull is greatly different when in the water so....what now ?
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Old 04-04-2010
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Yes the hull should be supported by the keel when on the hard. It should be supported by 5 stands minimum, or possibly 7. They should support the boat but not carry a lot of weight. And with a liner there is no easy way to visualize the inside portion.
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Old 04-04-2010
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The hull deflection from the cradle pad just looks like a careless job adjusting the pads on the cradle to me. Of course the weight should be on the keel with the pads providing lateral support... deflecting the hull means there's too much load on the pad (and more importantly, on the hull)
but,
there is no way you should be able to deflect the hull with your hand. I can do it on my Laser but definitely not on my CS27. It does feel like concrete when you hit it... especially with your head.
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