This issue is so common in the early to late 70’s boats. I must admit not to have had the opportunity to inspect any newer models. I would like to think that this problem would have been acknowledged and rectified.
What is the centre plate pivot pin for? Well, it does what it says, the centre plate hangs and pivots on it when lowered and retrieved. The slot in the centre plate fits over the pin, hence there is a lot of weight and vibration.
So what forms and supports this pivot pin? In the 70’s boats, not a lot!
This shows what’s left of the pivot pin and its turned boss support, there was no second boss! This is the turning at the top of the picture. The side cheek of the centre plate casing had 1 of these turnings bonded to its 2 side walls; I say bonded, using an epoxy adhesive of sorts. Given that these walls are no more than 5 mm in thickness, one’s centre plate was swinging and vibrating on such a flimsy device. Note that a previous owner had tried to stop the water ingress into the boat by winding nylon cord around the neck of the bolt. If it had been hemp with heavy grease you would have had half a chance, but this is a plumbing repair technique.
In the case of Lugger Angie in April 2021, before she joined my charter fleet in the South Ionian Sea, I noticed a rusty line in the bilge below the pivot pin area! “Ah!”, I said “that’s not looking good”, and behold a totally destroyed pivot pin hole, worn very much oversize by the weight and vibration. There was no pivot pin boss, just an oversize hole in the casing. The bolt head side has a washer and string added then poor glass matting applied over the side areas of the bolt head. There was a boss in position on the Starboard side, but loose.
The work now starts. As always good preparation is essential; the area is going to be heavily contaminated from salt water, possibly oil and the like. So abrade back the full area beyond the pivot pin hole, I would recommend 80 to 100 mm each way, then after vacuuming out, a couple of good wash outs with Gun Wash thinners, which decontaminates and breaks down the existing resin surface. You will note it goes a little tacky.
JLJ has had pairs of 5 mm thickness 304 Stainless plates made up with the pivot pin hole centre drilled so that the bottom of the plate sits on the floor casing, this gives additional support.
This is Angie, our MK1 Lugger, so no side casing and access is easy. Wetted mat is applied behind the degreased plates and aligned. Using the 4 screw positions drive in 15 mm x 4 mm screws just to keep it in position until the resin has gone off, they can then be removed.
To complete, fully glass the plate with overlapping strips of wetted out mat, exceeding the outer perimeter of the plate by 60 mm plus.
Coming back to my present MK2 Lugger Katerina we have cut away some of the outer casing to gain better access. There was some serious amount of poorly applied glass matting to be cut away. After several hours of cutting and grinding we found what was left of the pivot pin, I do not think it was the original, with only one pivot boss visible on the Starboard side.
We got back to the casing but it was not a good flat surface to work on, so I had to adopt another method of bonding the support plates on. You will note again this oversize casing hole! The other side still had what was left of the pivot pin boss.
To pack out the strengthening plate I made up ‘cigar rolls’ of wetted mat this to help bridge the cavity in the uneven surface. Then the 2 plates were assembled into position with the pivot pin bolt through. We did not tighten the nut at this stage but waited until the resin was starting to activate so the matting was just pliable and able to fold, this created a good cavity pad behind the plates. It’s a common mistake when using adhesives and sealants to pull the components tight together initially; all you are doing then is squeezing out the sealant or compound. Leave it harden off a little and then apply some pressure, by this stage it is now a form of gasket.
The both plates are now assembled with their backing mat/resin cured. We did not need the alignment holes in the plate since one boss gave us the lateral position, and it’s quite easy to align by eye. To complete, the plate and overlapping area is now glassed in. Note the blueish translucent smooth colour to the resin and how it exceeds the plate area.
To finish this work off the bilge and floor area is prepared and coated with Danboline protective paint. What a difference it has made! Another worthwhile task completed.