Thread: Material for timber bowsprit construction ?

Permapine would probably be the most durable.
Followed by expensive stuff like Huon Pine.
If it is just a spacer carrying compression loads on its wide face, almost anything will do.
Except maybe Paulonia or Western Red Cedar.

To keep it from rotting again, encapsulate in epoxy.

Place some thin copper sheet under both the bow sprit and between the spacer and deck. Bed well in polyurethane or polysulphide. Epoxy encapsulation may work, though doesn't work well on large diameter timbers. If the sprit or spacer is a laminate of thinner, encapsulated pieces, then yes, epoxy will work. If it's a solid hunk of wood, it'll check, split or other wise do what big pieces of wood do and no epoxy coating can tolerate this level of movement.

In short, if it's a solid timer, use copper sheets to isolate and poison and beasties that might want to live in places you can't see.

Hi Martin,use to have a 28 Swanson, Sirrocco 2 ,but it was plastic and certainly didn't have a bow sprit. Got any pictures.
What part of the Blue mountains and where is the boat.
Ian L

Originally Posted by PAR

Place some thin copper sheet under both the bow sprit and between the spacer and deck.

Thanks PAR and AJ for the replies, and apologies for my being a bit slow on the uptake.
The issue that I have is the rotting of the forward facing endgrain, so PAR with the copper, are you talking about encapsulating the entire chunk of spacer with copper ? Or just putting flat sheets of copper between it and the deck/bowsprit ?

And AJ, again excuse my dumb questions, but when you say to "encapsulate in epoxy", do you mean to paint on a West-System type resin/hardener ? Or do you mean using fibreglass matting in the usual way to fully enclose it and stop the water getting in altogether ?

Cheers,

Martin

Originally Posted by wavedancer

Hi Martin,use to have a 28 Swanson, Sirrocco 2 ,but it was plastic and certainly didn't have a bow sprit. Got any pictures.
What part of the Blue mountains and where is the boat.
Ian L

Hi Ian,
We live up at Springwood, but Scaffi (Swanson 28) is on Lake Macquarie aand has been for about four years- which is a bit of a way to commute, but we manage to get up there quite regularly (except when it rains every weekend for months on end..... )

I'll try to attach a photo of Scaffi, and you can see the bowsprit, 'though the spacer underneath isn't so clear.



I do recall visiting Sirrocco II, maybe at Refuge Bay or Pittwater or Sydney Harbour, about 10 years ago ? Again my memory may be playing tricks on me but I vaguely recall she has a small bumkin/rear deck to extend the cramped cockpit a little. As you can see in my picture, Scaffi has one too, and some people would say it makes the boat a little aesthetically challenged....... but it's functional.

Cheers,

Martin

A copper sheet is the traditional way of separating two pieces of material that will see constant dampness. It's bedded in sealant (tar is traditional) and only on the bottoms of the pieces affected. This doesn't mean you couldn't solder up an enclosure for the spacer, but I don't like that idea much, as it's likely to just trap moisture as well. You could also butter the whole spacer with tar, though this is a messy alternative.

The key is drainage and faying surfaces, usually, but if you have standing water getting at the forward end grain, maybe just something as simple as a heavy radius on the leading edge, so water can shed around and aft.

The problem with epoxy on timber thicker than 1" (25 mm) is the environmental changes can't be contained by just an epoxy coating. Simply put a 2" (51 mm) thick timber, even well coated with epoxy will move (change shape) sufficiently with temperature changes, that the coating will fail. Testing has found that 1" is about as much as you want to go in timber thickness, before you consider lamination. I take this a step further on certain hardwoods, which can move more than softwoods, so I limit these to 3/4" (19 mm), before considering a laminated piece to get the height necessary.

Since you're looking at a new spacer anyway (my assumption), make it from multiple pieces, to the height you need, if it's over 1" tall. Of course, encapsulate each piece, including screw/bolt holes, notches, etc. Then glue these together (more epoxy) to make up the spacer you need. This will last a lot longer then a single hunk of wood and will be slightly stronger too.

What are the physical dimensions of the spacer? For more information about epoxy encapsulation, log onto Epoxy by the Leading Epoxy Manufacturer | WEST SYSTEM Epoxy and download their free user's guide.