Thank you both.  I have been planning on using polyurethane, so have spent many hours getting the hole as smooth as it can possibly be - hence the question.  Now I just need a dry day to finish off!  Good luck Annie - it seems like you are in the final stretch.

I have another question related to the boat, but it is about steering, so I will post it in Scott's topic.

Mark Case wrote:

Everything seems to be going very slowly, although there is a lot of other work also being done that is not directly junk rig related.  I guess I am averaging 15-20 hours a week on the boat now the weather is better, but each job takes at least twice as long as expected!

Tell me about it, Mark.  You have my very real sympathy here.  At one time I was jesting about finishing SibLim 'sometime this decade'.  But there are times when I seriously wonder ...  All you can do is keep plodding on and remember why you're doing it.  It will all be worth while, when you pull up that sail and feel the boat accelerate away under you.

The biggest decision coming up is whether to glass fibre the hole through the partners - made up of eight layers of ply. It is very smooth and pretty well soaked in epoxy, and I am tending to think that glasswork will just add hours of smoothing that I have already done.

Personally, I see no point in adding fibreglass for the sake of it.  If you want extra strength (eg in my tabernacle and skegs), it makes sense; if there is likely to be chafe, it makes sense, but if you've put at least three thick coats of epoxy, there should be no issue with damp penetrating.  One layer of relatively light 'boat cloth' can make that easier to do.  I'm happy just brushing it on with a small brush.  If you are going to hold the mast in with a poured polyurethane 'gasket' like David Tyler does, I shouldn't bother with glassing.  If you are going to use wedges, one layer of 'boat cloth' should be sufficient to give you a nice, hard surface in case they do move, although I doubt I'd bother with it myself.

Brilliant!  I love the out of the box thinking.  I will have a poke around under the sole next week, but that sounds like a very sensible and attainable solution.  Many thanks, David.

Mark

I have uploaded a photo here of the place where the foot of the mast needs to go - between the main bulkhead forward and my size tens at the bottom of the picture.

The maximum depth beneath the cabin sole is about five cm, by my best guess, reducing to less than half that forward under my wellies.  Having looked again, and with my usual decisiveness, I am now leaning back towards plan a - three or four layers of ply built up on top of the existing glass fibre cabin sole, completely filling the available space, with the mast step on top of that. The other option would be to remove the glass fibre sole and build up a wooden one from the hull, but it seems to me that option will add complication without giving much in the way of extra strength and some further reinforcement of the bond between the inner and outer mouldings under the berths may help me to sleep better at nights.

As always, though, I am keen to be corrected if my thinking is awry.

Many thanks,

Mark

Hi Mark,

my question is how well is the liner fastened to the hull? As the lateral forces from the mast will be transferred to the liner in your suggested solution, and not to the hull, then this could be the critical junction. It may be advisable to investigate this further and if doubtful then cut through the liner and fasten directly to the keel, possibly incorporating the liner into the mast step as it passes through. What is the distance between the liner and the keel? I am assuming both are fiberglass. One way of doing it may be to build up with composite plywood and fiberglass solid from the hull to the liner and then build the mast step on top. Of course it all depends on access to the space.

All the best with the project, David.