This is why I say to glue up a solid topmast from small pieces - the knots and flaws will also be small, and you can stagger them so that they are surrounded by stronger timber. Look for 2 x 1 or 3 x 1 construction timber with the least flaws. That would be "good enough". Filling the knots won't help the strength; cutting them out entirely and scarphing back together would, though I think that's going too far. What all this amounts to is Glulam, widely used for enormous buildings these days. Check out the specs for knots at this supplier, for example.

For the first unstayed mast I ever made, I simply went to the woods and cut down a cypress tree ( after asking the owner, of course). Trees are engineered by nature to stand up to wind and not break - and they have knots!. 

Looking at your jaw-dropping record of achievement in the mountains (I speak as an ex-scrambler/hillwalker who has stood at the foot of El Cap and marvelled), I imagine that you'll be doing similarly amazing things in your Hurley 22 in due course, and for that, the soundness of the topmast will need to be beyond doubt. The small alloy tube with plywood rings is not. 

The boat is in Galway, I see in your profile? This is a large city with multiple sources of construction timber. A quick search brings up Woodcut who can probably supply specialist timber (or even make the topmast for you), but white deal from McDonogh will do perfectly well for a solid built-up topmast, if used in small sizes that have been selected to be as clear and straight-grained as possible. Another source would be Curran Sawmills who can supply spruce, douglas fir, pine and larch, all suitable.

Anonymous wrote:

Ever since I started rebuilding my boat, and going down the junk route, I've found myself awake at 3am, not thinking about all my regrets, like most 50+ year old men, but about subjects such as "does my Origo stove really need a gimble?". 

One subject that keeps me awake is making the top part of my hybrid mast, without ending up with something that looks like Harry Potter's wand.

I'm currently making a new rudder and skeg, based on Arne's PDF A new rudder for an Athena 34 in which he makes a rudder from slices of 25mm plywood, threaded onto stainless steel stock, which is then fibreglassed. This appeared to allow a complex shape to be reproduced quickly, from a template.

This got me thinking if it would be possible (I'm sure it's not), to use the same technique to build the top section of a hybrid mast?

Happy for this dumb and dumber idea to be picked apart.

Oh, and does a stove really need a gimble????

Best

Andy

The use of the comparative degree, 'dumber', reminds me of my English grammar lessons, and I would like to gently suggest the superlative degree with respect to this mast idea. Plywood discs would add no bending strength, only weight (acceptable for a rudder, but not for a mast). Only longitudinal fibres add strength, whether they be of glass or of timber. 

If the aim is to deskill the construction, then a simple solid timber basis might be a four-square central section consisting of four full length pieces of 35mm x 35mm, with the inner corners chamfered off to provide space for a cable, so that the top can be finished at 70mm diameter; then further shorter 35mm x 35mm pieces glued on at the lower end so that it can be finished at a diameter of 140mm to fit inside the tube; then further even shorter pieces just thick enough to form a shoulder. The length of these shorter pieces determined so as to permit planing and then sanding down to a round-sectioned half-barrel taper. The quality of the timber need not be so high as for a lighter, staved construction. I cannot see more work in this than making a large quantity of discs and glueing them together.

Oh, and no, a small boat's cooker need not be gimballed. I've found it better to mount it on a shelf that is hinged about a fore-and-aft axis, with means to fix that shelf horizontally for most occasions, but also to fix it at a +/- angle of maybe 10˚, 15˚ and 20˚to the horizontal that suits the rare occasions where one needs to cook when thrashing to windward. This is easier than trying to make a stable set of gimbals.

Ever since I started rebuilding my boat, and going down the junk route, I've found myself awake at 3am, not thinking about all my regrets, like most 50+ year old men, but about subjects such as "does my Origo stove really need a gimble?". 

One subject that keeps me awake is making the top part of my hybrid mast, without ending up with something that looks like Harry Potter's wand.

I'm currently making a new rudder and skeg, based on Arne's PDF A new rudder for an Athena 34 in which he makes a rudder from slices of 25mm plywood, threaded onto stainless steel stock, which is then fibreglassed. This appeared to allow a complex shape to be reproduced quickly, from a template.

This got me thinking if it would be possible (I'm sure it's not), to use the same technique to build the top section of a hybrid mast?

In my example, where I have a 152mm x 5 metre pipe, with 6mm wall thickness, and I need a 2.5 wooden top section (based on a Corribee mast, which just looks 'right'). Could I take a 50mm (6082T6) tube, as the spine of the mast (this allows me to easily run cables), and then build up the body of the mast with 100 x 25 cm thick disks of exterior plywood (you could step them down from do 140mm, 120mm, 100mm using a hole saw), which are stacked and epoxied onto the pipe, then glassed. You could sand the steps down to achieve a more tapered appearance. I suppose you could increase the size of the pipe to create a lighter and stronger mast. A sheet of 25mm plywood, some hole saws, and a length of pipe would come to less than 100 euros, and might achieve a more practical solution to anyone who is not already a master spar maker (or who knows one).

Happy for this dumb and dumber idea to be picked apart.

Oh, and does a stove really need a gimble????

Best

Andy