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Go Back   SailNet Community > On Board > Gear & Maintenance > Installing Additional Keel Bolts
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Thread: Installing Additional Keel Bolts Reply to Thread
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Topic Review (Newest First)
11-24-2012 07:41 AM
Ajay73
Re: Installing Additional Keel Bolts

Per Stumble: "For instance, have you considered how the new bolts are going to be bolted to the boat? Is there sufficient structual support there to take the potential loads? If not you could over stress a non-reinforced section of the hull quickly.

Bolts are typically spaces far enough away that their compression loads don't merge. Adding new ones can screw up this careful placement, and create peak loads beyond the safety margins."

The Catalina 27 keel sump is the same throughout its entire length. The sump isn't built up around the bolts and thinner between them and it doesn't have a structural grid. The additional bolts would be place halfway between the existing bolts, certainly not close to an existing one. Others with C27's have added bolts in cases where the existing ones are thought maybe to be weakend from corrosion.
11-24-2012 07:31 AM
Ajay73
Re: Installing Additional Keel Bolts

Quote:
Originally Posted by msmith10 View Post
I have to agree with Stumble. It sounds like you're trying to fix a nonexistent problem. If Catalina felt additional keel bolts were good, why didn't they put them in when they designed/built the boat.
I'm not trying to fix anything. It's not a fix situation. It falls under the category of an improvement, additional strength. I'm sure that Catalina determined that the six bolts was sufficient but they also told me that the addtion would be an improvement and saw no downside.
11-23-2012 06:01 PM
msmith10
Re: Installing Additional Keel Bolts

I have to agree with Stumble. It sounds like you're trying to fix a nonexistent problem. If Catalina felt additional keel bolts were good, why didn't they put them in when they designed/built the boat.
11-23-2012 04:28 PM
Ajay73
Re: Installing Additional Keel Bolts

I had contacted West System's tech support and they thought there would be no problem with this approach.

I'm not trying to eliminate a smile but just trying to add safety margin for not too much work. I also talked with Catalina engineering and they said adding additional bolts would generally be a good thing.

I'll have to call Catalina Direct and get more info on the lag bolt method.
11-23-2012 04:10 PM
overbored
Re: Installing Additional Keel Bolts

if you are trying prevent or eliminate the Catalina smile then use the kit from Catalina direct. the kit does work well and is a tested method but must be done out of the water so the boats weight is pushing the smile closed before you drive in the lag bolts. the lags will not close the smile with the weight of the keel hanging
11-23-2012 02:08 PM
addict
Installing Additional Keel Bolts

Catalina direct has a lag bolt kit.
11-23-2012 01:29 PM
Stumble
Re: Installing Additional Keel Bolts

Rarely is it justified to install additional keel bolts. And other than on high end racing boats I have never seen a reason. While they may look it, keels are not just slabs of lead bolted to the bottom of boats, they are highly engineered items, with a great deal of thought and work by engineers to figure out how many bolts there should be, and where they should go. Adding new ones is rarely going to add any more safety, and may weeken the entire structure.

For instance, have you considered how the new bolts are going to be bolted to the boat? Is there sufficient structual support there to take the potential loads? If not you could over stress a non-reinforced section of the hull quickly.

Bolts are typically spaces far enough away that their compression loads don't merge. Adding new ones can screw up this careful placement, and create peak loads beyond the safety margins.


Finally as to your method... It would work, for some definition of work. But no i wouldn't consider it sufficient. Lead is very soft, and can't take much sheer load. This is exacally why keel bolts aren't just tapped into the keel. The J shape is is increase the area of load distribution, and to put some of the lead in to compression, as opposed to tension. What you suggest could work, but would require some real engineering to figure out how large the hole would need to be to provide sufficient bonding area to support the loads you would face.

In short, I see this as a lot of work and cost, for minimal if any gain, and a real possibility of damaging the boat for no identifiable reason.
11-23-2012 01:15 PM
Ajay73
Installing Additional Keel Bolts

I have a 1980 Catalina 27. It has a lead keel. I'm thinking of installing a couple of additional bolts and wondered if anyone has used or thought of this approach: drill a slightly oversized hole, attach a nut at the bottom of the new bolt and using a thickened epoxy fill the space around the bolt and nut. The alternative method usually says to cut a window in the side of the keel and affix a washer and nut using this window. Having used epoxy for a lot of boat projects and a good appreciation of its strength I would think the first method would be acceptable. Any thoughts?

 
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