hull deflection

[OCD]

I took a second look at a Tanzer 22 today. The boat seems to be generally in good shape but I noticed something on my second tour.

The hull, which is in otherwise great shape, is deflected underneath the pads on the trailer. There are no obvious signs of stress around the depressions. I know that the boat has been sitting on this trailer for at least a year (maybe 2). BTW - the pads are not adjustable height-wise.

Is this deflection permanent, will it rebound when the stress of the pads is removed? Should I run in the other direction?

[Sasha_V]

Lightweight performance boats seem to often have this issue. A Northshore38 belonging to friends used to dimple up around the keel when it was on the hard stand in a most alarming way.

The simple answer to the question is that you should not buy the boat until it has been for a sea-trial with you, get it off the trailer and into the water. Check to see if the dimples pop out cleanly. Know that any hull that gets flexed around hardpoints like that will develop weakness at that point. It may be so slight a weakness that it is completly insignificant, or it may be something that requires thought and attention. Hard to say without being there and knowing details of the boat''s construction. If it is a cored hull, then it WILL be an area for increased risk of delamination.

Float the boat, see if you like it enough to get a survey done, then buy or don''t buy. If you want to just make a desicion on a whim then you will never really get use of the boat anyway, as another whim will come along shortly and the boat will spend two years on its trailer in your yard instead.

Sasha

[OCD]

Sasha,

Are you chiding me? You''re right of course and don''t worry... I''m patient. I''ve spoken to a couple of surveyors. Although one thought, like you, that it may or may not be a problem another didn''t even want me to waste my money on the survey. I''m thinking that the search will just have to continue. Thanks for your thoughts.

peter

peter

[Jeff_H]

I basically agree with Sasha on almost all of his points. Deflections at supports are pretty common on older production boats. Whether they are a serious problem or not is highly dependent on where they occur, how deep they are and how the boat was constructed. That kind of call is best made by an experienced surveyor or repair yard. I would suggest that you discuss a limited scope of service with the surveyor. In other words, contact the surveyor and explain that you have a concern about this problem. In advance negotiate a set of fees from the surveyor that assumes that if the problem is serious you will not proceed with a full survey, and only pay him for his time and expenses to make that call, but if the problem is minor, then you will proceed.

I somewhat disagree with one minor point in Sasha''s otherwise good advice. Sasha said that deflection like this is typical on lighter performance boats. I disagree. Light weight performance boats are generally engineered to be quite stiff and so have the kinds of framing to minimize this kind of deformation. They may also bve cored which further would reduce the likelyhood of deflection. But fiberglass is very flexible as a material but loses strength over time when deformed. This kind of deformation is far more typical on volume production boats and even on pretty heavily built cruising boats that lack proper framing and/or coring than it would be on lighter performance boats were the loads aree smaller and the engineering and build quality much higher.

Respectfully,
Jeff