mast wedges

[Murray Campbell]

So the wind died and left me pitching around in a slop....it threw a bunch of the mast wedges out...it's happened before and i really need to correct this

haven't seen a lot written on mast wedges....mine were driven from the bottom but perhaps they should be driven from the top?

is there a correct taper?

(my "partners" are a big piece of steel pipe so there is no taper in the partner, is this the problem?)

thanks guys, m.

[Dan McCosh]

Mine are driven from the top. They are a fairly narrow taper, with a notch to keep them from slipping through when the mast moves. I use soft cedar, and they lay against a bronze collar.

[Ian McColgin]

Dan has the right idea: Some sort of soft wood, gentle taper and maybe a lip, driven from the top.

If the taper is gentle enough that you can just start the wedge and still tap down till the bottom of the wedge is just below the bottom of the partners, you'll have a nice long pressure on the mast.

Have a purpose shaped bit of wood that is a little smaller than then smallest space between mast and partners. Helps in driving wedges in and is totally necessary in getting them out.

Back out the inside and round the outside if you're wedging a round mast.

There are boats where the allignment of partners to mast step is a bit off for whatever reason, typically fore and aft - should not be athwartships. While a little spring to the mast induced by tuning will not generally hurt, you may want to have different sized wedges on one side than the other and absolutely the fore and aft wedges may be different than those on the sides.

Once you have made a good set of wedges - all the way around virtually nothing in the way of gaps beween. I start with the center wedge forward being "F" and move around the sides with S1, S2, S3 ... and P1, P2, P3 ... till we get around the "A" on the aft side.

G'luck

[Jim Budde]

On an unstayed, 13'8" (3" dia at partner) mast, how many wedges are needed? Plans use the singular word .. wedge .. implying one, as opposed to the plural ... wedges.

[Murray Campbell]

Thanks.

I'm going to try a much more gentle taper, a lot more wedges, and i'll get them in properly from the top.

Is this the time to slack the standing rigging off and set the mast rake? I'm guessing that i should try to get that pretty close to where i want it at this stage.

[Dan McCosh]

You ought to set the mast rake before cutting new wedges. This helps to prevent putting a bending point at the deck level, where the compression loads are highest.

[Carlsboats]

Sparkman & Stepehns put me onto a different way
of wedging at the partners -- use an elastomer
instead of wood, and wedge only fore and aft, not side to side. The way they suggested to me --
and the way I have done it for a good many years as a result -- is to get some fairly dense neoprene from an industrial supply house, sheet
stock from 3/8" to 5/8" thick, depending on your needs, and put the rubber wedges down the aft quadrant of the mast. This should not be really soft stuff, like foam, nor should it be as hard as a hockey puck -- it should be stuff you have to push to get your thumb into. Then put a purchase just above the partners, a block and tackle or a line to a winch, and pull the mast aft as hard as you can. Tuck rubber wedges down the forward quarter of the mast.
When you release the tension, the mast springs back forward a little and the wedges are firmly captured. You can put a light lashing around the wedges to be sure they don't come loose, but in my experience they have never moved. Of course, as usual, you need a canvas rain collar to finish out he job. Advantage: The mast is free to move a little, which is what a keel-mounted spar ought to do to take up shock loads.

[Ian McColgin]

I don't understand how compression loads on a mast are concentrated at the partners, at least not the verticle compression loads of the stays. The push of the mast wedges is a compression load around the mast, a bit higher on the concave side. Some structures will fail if bent on a fulcrum, which the partners certainly are, that could bend further if bent with more distirbuted flex.

But at any rate, while I've not seen a mast harmed or compromised by the modest spring you might induce by fine tuning or raking the mast a little after putting the wedges in, I still believe it best to do the first at-the-dock-not-really-cranked-down-too-hard-yet tune with wedges out.

Wedges should fit nicely. This generally means that they should not be so large that they rub the partners and mast too much more on one side than the other. I generally make mine about 1" on the untapered sides. I normally plane the taper on the face that will be against the mast as this takes less splinter beating on being driven in.

There's nothing wrong with gaps between wedges so long as they are not much more than 1/32" or so.

Wedges for a rectangular mast can be a pain. I usually have the sides gang up right from the front of the partners to the back and set them first. Then the forward and after wedges can be tapped in, nestling between a little bit of the side wedges.

[Dan McCosh]

I was being simplistic, but the point was that by the time you get to the deck level, the weight of the mast combined with the vector thrust of the rigging is quite high. This is a bad place to put a hard point that acts as a fulcrum for a bending load, such as you ger from headstay or backstay tension. The idea is to maintain a column load down to the mast step. At one point, I had a set of medium rubber wedges, although I now use soft cedar. I don't quite understand why you would want to use foam at the side. It seems as if that would put the column load out of line in several situations.