Making good over-bored holes from wasted fasteners

[Sniper]

I am in the process of replacing bolts which go through steel galvanised floors, keelson and deadwood. These bolts were originally about a foot long but have now wasted away and in the process have degraded the surrounding wood. I have removed the remnants of the bolts but am now left with holes to fill prior to fitting new bolts.

My plan is to over-bore the holes sufficiently to reach sound wood and then epoxy in dowelling of the correct diameter to fill the holes snugly. I will then re-bore the holes for the new bolts, which are likely to be around 3/8 - 1/2 diameter. Does this sound like a sensible way to proceed or is there a better way?

Boat is 28' carvel built Twister.

 

[Poignard]

A fine boat!

If you download the WEST Wooden Boat Restoration & Repair manual ( http://www.westsysteminternational.com/en/west-system/wooden-boat-restoration-repair-manual ) and look at Section 5.7.1 you might find that helpful.

 

[d4dunmor]

Establish how much material you need to remove . Next size up either metric or imperial may work
Dowel produced from end grain will have different characteristics
An oversized drill bit with the front spun down to the existing size hole will follow original hole

 

[Sniper]

Thanks for the responses. I'll crack on!

 

[Prasutigus]

Greetings,
I have just read a piece about R K-J's Suhaili being restored. It doesn't go into details, but they replaced every fastener.
The Sailing Today mini-interview quotes him as saying there were managing to replace 8 a day, then started another method which let them replace 80 a day ( 2-3 people working.)
I think they did it at the Elephant boatyard up the Hamble.
I don't like the sound of dowel, with the end grain able to suck up sea water.
Perhaps you can let us know what method you use in the end, thanks.

 

[martinaskey]

On the assumption that these are the keel bolts, that they are threaded into the top face of the keel and the the operation is being conducted without removing the keel ........................

I'd be very tempted to try oversized keel bolts with minimal removal of wood but it depends on how badly degraded the wood surrounding each hole is. Clearly a lot of degradation would mean a massive keel bolt !! The thread in the keel will of course be too small for the bigger bolt but the last section could be turned down to the correct diameter and thread.

My concern with the dowel approach would be that it cannot be reversed - if is doesn't work you are left with a bit of a mess. I'd also be worried about my ability to bore the dowel plug out with enough accuracy to give the snug fit required in exact alignment with the original keel tapping . But you may be more confident than me about this.

Two things I've found useful when replacing old keel bolts - length of plastic tube attach to the vacuum cleaner and suck out the rubbish that has fallen into the threads when removing the old bolts. A thread tap welded to the end of a rod to gently clean the threads in the keel before inserting the new bolt (careful not to get it stuck !).

Hope that helps

M

 

[alant]

I am in the process of replacing bolts which go through steel galvanised floors, keelson and deadwood. These bolts were originally about a foot long but have now wasted away and in the process have degraded the surrounding wood. I have removed the remnants of the bolts but am now left with holes to fill prior to fitting new bolts.

My plan is to over-bore the holes sufficiently to reach sound wood and then epoxy in dowelling of the correct diameter to fill the holes snugly. I will then re-bore the holes for the new bolts, which are likely to be around 3/8 - 1/2 diameter. Does this sound like a sensible way to proceed or is there a better way?

Boat is 28' carvel built Twister.

Are the new bolts going into the same holes?
If not, you can 'blank' the old holes with a trennel, saw them on a recent restoration, basically a big wooden dowel (treenail) which pushes into the hole & is held using a centre wooden wedge, the whole lot being cut fair with the hull.

 

[Prasutigus]

Are the new bolts going into the same holes?
If not, you can 'blank' the old holes with a trennel, saw them on a recent restoration, basically a big wooden dowel (treenail) which pushes into the hole & is held using a centre wooden wedge, the whole lot being cut fair with the hull.

Still commonly used in Norway for numerous Viking longboat replicas etc, juniper is the timber of choice, and lots of tar.
Block up the old holes with juniper trunnels, and drill new holes might be a plan?
I haven't done it, but I would.

 

[john_morris_uk]

I had a similar problem and fitted small graving pieces into the strakes. (Garboards plus two up on either side.) The graving pieces were let in on tapers and epoxied into position. This was all in the advice of my surveyor. Several years later, when we sold the boat, the purchasers surveyor insisted I steam shop new sections of strakes into place with 6:1 scarfing joints plus backing pads behind the joins.