Mast alignment in mast partner

[Patrick_Seattle]

I had my rig down all winter and it's been back up a month or so. I have a keel stepped mast.

I had a rigger come out and do the initial tensioning of the rig and the mast was just touching the partner on the forward edge. I loosened the rigging and worked the step back a bit and it all looked straight. I had the rigger come back out and now it looks a little to one side and still pretty close on the forward edge.

I wanted to use spartite on my mast but it seems like there so little clearance with the mast this way.

Should I be that worried about the mast being perfect spaces in the partner? I'm trying to figure out if I'm being too picky or if I should be loosening the whole thing up and going back to the crane to get this right.

Thanks,
-p

[Ian McColgin]

I live with wooden boats where sometimes things move and sometimes you want to move the rig about a little so:

You referr to 'mast step' but the place where the mast goes through the deck is the partners. The step is where the mast lands at the bottom. Many steps are absolutely where they are, period. But some have a little adjustment fore and aft via wedges or a screw.

Further complicating is that the scantilings for a deck stepped mast are usually a bit heftier than for keel stepped as the deck stepped lacks the support that comes from the partners.

Further, the partners give you a way to craft a bend in the mast that you can't do so interestingly.

We woodenboat types don't like poured wedges. We make wedges that fit the way we set the mast, which is sometimes a bit at varience with how the builder made the step to partners alignment.

I'm going to assume from your question that neither you nor your rigger has any interest or expertise in using the partners as part of bending the mast, so cutting to the chase: Brion has some excellent info on how to tune the rig. Do that on a nice day - breeze but not so much wave action that the mast pumps and you can do it with the wedges out. Get it right. Then wedge.

Gluck

G'luck

[Patrick_Seattle]

Ian thanks for the reply. Not sure what you're trying to say though.

Let's clarify some terms, maybe I'm using them incorrectly.
I have a fiberglass ketch with a keel stepped main and deck stepped mizzen.

The mast partner in the case of my fiberglass boat is just the whole in the deck. Maybe we should just call it the hole in the deck, but everyone calls it the partner. It is not adjustable. The maststep is adjustable it's aluminum sitting on a UHMW block and has four lag bolts into the keel.

For those playing along at home here's traditional wooden mast partner:
http://www.aandc.org/research/mast_partners.html

I'm talking about the fore/aft placement and twist of the mast as I can see it where it goes through the mast partner (AKA the whole in the deck). After the tensioning of the rig and measurement to make sure the masthead was centered the mast is pulled to one side in the partner, a tad twisted and is definitely pulled very far forward in the partner; 1/8" from touching.

I'm just trying to determine if I should be worried about the mast placement not being centered in the partner (aka hole in the deck) or is it not a big deal.
I also assume that if it does need adjusting it's not through the wires, but through getting the maststep into the right place.

Thanks,
-p

[Ian McColgin]

I don't worry much about fore and aft centering at the partners. But if you have an adjustable step, you ought to be able to reduce or eliminate any asymetry there as desired.

Failure to get athwartships centering there could well indicate a subtle bend to the mast. I've always taken that out by wedging. You can't do that with poured stuff, only real wedges made for the purpose.

Before deciding, I'd check the scantlings and the rig design - staying and all. On many boats no weight advantage is taken by having keel stepped and the mast walls are just as hefty as deck stepped masts need to be. This may be to achieve extra strength or because of what's out there on the extrusion market or builder indifference or rerigging along the way.

Do you have a mast and rig designed to take a bend, or is your main (I'll ignore the mizzen for now) really designed as a straight column? Even if the latter, I'd be inclined to force athwartships symetry at the partners if I was dead certain that the hole and step are both themselves perfectly centered. It'd hard to see a subtle curve but there have been columnar masts where I could sight from the step through the partners and see a curve. If it came out with a bit of creative wedging, that was nice. In other instances, the tune was right even though the mast leaned against the foreward side of the partners hole. If no adjustment in the step, I'd wedge it thus.

Part of my prejudice about poured wedges is the nightmare they cause in stepping and unstepping. Most boats with aluminum masts (parallel sided extrusions in that area) also have parallel sided partners. So getting things in an out is a royal pain. One boat that was a constant horror I finally solved by shaping a very subtle taper into the partners such that the poured wedge only got really firm when gently tap-seated after the mast was in the step. Comes out more nicely as well.

G'luck

[CAM]

The two important points when initially setting up a mast are the top and the bottom. You can't move the bottom side-to-side (generally), and you want the top centered. You want the rake where the designer intended, or somewhere different if you are curing a balance problem. Very few partners will be centered on the mast in either direction on a production glass boat, just don't worry about that. Most glass boats will have some taper at the partners (called "release" in mold making). Spartite is used all the time by folks that frequently step and unstep their masts.

[Jim Fulton]

The original question had to do with whether it is a problem if the mast is not centered in the partners. It may be that the mast is in the right position but the boat is not perfectly symmetrical--few boats are, particularly older boats. If the mast is positioned and tuned as well as you can get it, I wouldn't worry much about its position in the partners.

Jim Fulton