The removal of Enfys’ keel bolts is described in here. In this article, Bill Dowell continues the story by describing the installation of the bolts and the re-building of the keel case.
On the underside of the ballast keel the bolt head recesses were filled with mortar with a water-proofer added.
The exposed faces of the lower part of the centreplate case that is only accessible from under the boat were found to be a bit worn and ragged from the effects of immersion, lack of paint and the chafe from the centreplate. A simple scraper and wire brush on long handle was used to clean the barnacles and loose stuff off and the bare timber was treated with penetrating epoxy followed by a couple of generous coats of underwater primer.
The centre-case under bolts were plugged-over and the upper part of the centreplate case reassembled with newly-made sides in iroko. Sikaflex was used for all faying joints and it was here that I discovered a problem: the Sika has a problem with the underwater primer and seems to ‘melt’ it so that the Sika does not stick.
A new capping piece was fastened down onto the lower casing with bitumastic sealing strip. Epoxy sealer was used on all faces that were potentially going to get wet or to be covered in sealant. The casing was varnished and the cabin furniture re-fitted.
We had reassembled the front casing upright post exactly as the original which had the athwartships through-bolt passing through the joint – there was no ‘stop-water’ in this joint and we just relied on the Sikaflex to seal it.
After she was launched water started weeping in and appearing from under the lower capping. At first we thought this was coming up from the lower casing and extra screws were added to force this down. After a period afloat the ingress slowed but it continued for the rest of the 2019 season.
In early 2020 whilst ‘Enfys’ was ashore we re-visited this part of the centreboard case and took the cappings off. Assuming that the problem was the joint below the front upright post (‘headledge’) we made and fitted a stop water block in this gap well-packed with bitumastic tar and held in place by a new clamping piece.
The lower capping was cut down to suit and was refitted. This work was done on the eve of the March 2020 Covid19 lockdown and it was not until July that the yacht was finally launched. To my dismay she still leaked from this joint somewhere….!
The trickle continued all the time she was afloat, and, in the end, we were about to beach her or get her lifted out when we decided to have another look at the casing joints behind the front capping. This was taken off whilst she was still afloat, and we found she was leaking from the joints between case sides and the front upright. This was simply packed with caulking cotton which finally stemmed the inflow.
In summary we shouldn’t have used Sikaflex for sealing these underwater joints.
Owing to lockdown over the winter 2020/21 we were unable to plan any further work on this but will probably eventually resort to dismantling the upper part of the case again and re-doing the joints with an alternative sealing method.
This article was re-published from the Enfys blog at Finesse 24 Sailing Yacht: June 2019 You can read about the renewal of the stern post too, which was carried out at the same time.