Keel Flange

[Waypoint]

Hi,

I have a 38ft GRP yacht with a lead fin keel which is to the hull with 11 stainless steel bolts. When craning the boat out of the water this month there was a gap of some 5mm at both ends of the keel between the keel and the hull outside the area where the bolts connect the keel to hull. Would this be described as normal and due to the hull flexing? There is no water entering the bilge and the keel bolts are all tight.

Thanks for your input and advice.


<hr width=100% size=1>

 

[andy_wilson]

I think when your local GRP specialist surveyor or yard sees the difference when sitting and suspended, they are going to want to hav a good look at the floors or structural web inside the hull, which will almost certainly require reinforcement.

Has it been bounced on the bottom at all?

<hr width=100% size=1>

 

[30boat]

Are you absolutely sure that the bolts are fully tightened?The nuts should be retightened from time to time .On a 38 footer you should use a socket spanner with a yard long lever and apply as much force as you can.
I did my Fulmar this summer and despite looking tight I was able to wind them by a further half turn or more.
This should be done with the boat ashore to avoid undue stresses on the laminate.By the way are the plate washers large and thick enough for the job?

<hr width=100% size=1>

 

[vyv_cox]

I don't think that 5 mm is excessive. The gap on my 34 ft is probably 3 - 4 mm. The fact that the boat is dry is the critical point. There is always going to be some sag of the hull when the boat is lifted. Just in case, inspect the hull for any evidence of weakness or cracking when the boat is in the slings but I don't think you need to worry. Checking bolt tightness, as suggested elsewhere, is worth doing.

<hr width=100% size=1>

 

[Waypoint]

Yes, unfortunately the boat has been grounded whilst taking a short cut. However there is no visible structural damage either on the inside or outside of the hull surrounding the keel. That is why I was paying particular attention to the joint when the boat was in the sling. I would expect to see some flexing of the hull and I note that in the case of Beneteau, they mention the gap in the keel flange joint and recommend that it be resealed periodically. My question is whether I am right in expecting to see flexing of the hull on boats with long fin keels?





<hr width=100% size=1>

 

[Richard_Blake]

Re: Pub hearsay...

...for what it might be worth: someone saying a GRP boat had been distorted by over-enthusiastic tightening of fore- and backstays on a cutter. And did the gaps disappear when the crane or travel-lift put the boat down again?

<hr width=100% size=1>LowTech