Mast repair or replacement?

[Nanoose]

We went out to the boat today to remove the spars for refinishing and while we were there Deb noticed a section of rot in the top fourth of our main mast. We haven't looked at it closely but are trying to determine our options.

We believe the masts are original (Nanoose was built in '79) and they're deeply checked. I don't think that they're checking further now but have likely been that way for some time. This, coupled with a few years of neglect, has likely created an ideal way for rainwater to sit, unmolested, and caused the rot. The masts themselves are solid fir (I'm pretty sure) and are about 30 ft. I don't know the circumference but will check tomorrow.

I think our options are:

a.) Replace the mast. If we go this way, can someone tell me if this is a big deal or is it pretty straightforward?

b.) Scarf in a replacement.

c.) Replace the mast but scarph together two shorter timbers to get the full length.

Also, I'm assuming that Douglas Fir is the way to go based on both suitability and availability in the PNW. Comments on best wood? Sources (Vancouver Island)? And what should I be looking for when I evaluate the wood itself; grain, moisture, etc. (e.g. a friend has a hundred acres of forest - do we just go cut one down, drag it home and start whittling?? :o)

Thanks in advance for your help!

Dave & Deb

[Jay Greer]

A thirty foot stick is not very large. The effort to, properly, scarf on a new section is nearly or, in some cases more effort than making a whole new one. At this point, you have the option of making a new hollow spar that will make your boat stiffer as well as to allow you to run wiring down the center. A birds mouth spruce stick will be even lighter than one of Doug Fir. While many of us in your area are equipped to build masts, my spar bench will not be ready until the later part of spring. Check with the builders in Sydney if you are looking for a spar maker. Bruce Tipton of Port Townsend is also a very competent spar maker.
JG

[Nanoose]

Seems like this could be the best alternative and something that would be an interesting project too. I'm at that stage where my mind is trying to visualize how it would come together and I think the math (at this point) is close to making my head explode. (I have the same problem when I'm trying to wire three-way switches ).

We haven't had the sticks down but I'm pretty sure there is a taper. We also have a steel mastband, rather than spreaders, which rests on a shoulder. I'm not sure how I'd accomodate this in a birdsmouth mast unless I were to oversize the thickness of the staves.

The cost of doing it this way vs. a solid timber is attractive (I'm guessing 'cause the lumberyards are closed until New Years), and making it stiffer seems attractive too.

This will take some thought...and more wine.

Dave

[Jay Greer]

Tapered blocking can be built into birdsmouth spars in order to support localized loads. Most spar makers, who have been in the buisness a while, should be able to advise you. However, if your spar maker can not come up with reasonable answers for you, then you need the advise of a competent yacht designer.
This is not an advertisement for my services. Just an educated observation.
JG

[johngsandusky]

Option B: I scarfed repairs into my mast a few seasons back. It is also a solid stick, also checked. Using saws, broadhatchet, and chisels, I cut out the rot. I then tapered that cut into a fair curve using drawknives and spokeshaves, testing with a batten. Planks were sprung into this curve, glued and clamped in place. When dry, I cut the excess, and smoothed, faired, with drawknives and planes. It's strong, tight, and looks pretty good. This is just an enlarged version of a common way to cover knots or flaws in round spars.

[Ian McColgin]

Start gouging out the rot and see how far it goes. It may just be in the way of some fastenings and be easy enough to fix.

If you make a new stick that's hollow, common practice calls for compression blocks inside at hoops and at the partners. However on Goblin I found that her 60 year old masts had been made without compression blocks aloft, only at the partners. Think about it. How can an all around strain hurt a hollow structure. The partners, on the other hand, are less evenly loaded. If you make compression blocks, slant the top down to the center and put a fine center hole, which you may want for wiring anyway, to weep the inevitable moisture (condensation out of the wood) that will run down. Put an aft slant at the top of the solid part of the mast heel and a drain hole out down there. Again, this may also be a wire chase.

But think about changing to hollow and check a qualified NA first.

Example: Marmalade is faster than the only Chappaquiddick 25 she's sailed with. It's not the sails and it's not the hull (though that one is glass) and at least on some points of sail it's not that I was trying harder. The other Chappy was working through the chop with greater vigor, not to say violence. This was due to her hollow aluminum mast and gaff. With her 300# boom, 150# gaff and maybe 900# mast, Marmalade did not toss her sails so much and thus sailed better. A really concentrated moment arm is sometimes desirable but, depending on hull shape, may be a disaster.

G'luck

[Nanoose]

Went back out to put the winter cover on after removing the spars and had a better look. It appears that the mast has cracked forward and probably did so when we put things back on after refinishing the bow sprit. Chances are we cracked it when tightening the turnbuckle, we didn't really crank on it so I'm pretty sure that it was rotten at that point.

For now we're trying to source the wood for a solid stick. I think it's both easier and more "original" than a hollow mast would be. And, Ian made a good point about needing to check with an NA before I went too much further.

Ian, I'm not sure I get your point about Marmalade...does she have solid spars and is thus more balanced from a momentum standpoint?

Dave

PS. Jay, thanks for your reply and the note about the "not advertising". You're a straight shooter, I like that. Your opinions, advice and counsel are greatly appreciated always.

[Jay Greer]

Dave,
I would be happy to take a look at your mast free of charge. I will be in your area near the end of Jan.
Fair Winds,
Jay

[Nanoose]

Thanks, Jay, a lot! We'll look forward to connecting with you and formulating a plan then. Best wishes for a good new year to you and yours.
Dave (& Deb)

[Ian McColgin]

Yes, Marmalade's solid spars gentle her motion compared to the glass Chappy with aluminum spars.

the catboat form has so much initial form stability that the weight of the spars does not appear to add noticable extra heel while sailing. The point at which heeling moment from spar weight would make a difference is past the point of no return for a cat boat anyway.

I've seen narrower ocean going boats that are improved by a solid stick or two even if it did add some heeling. A shape like Spray and even Wm. Garden ketches (most of which have aluminum spars) get more pleasant with solid sticks.

[Nanoose]

We went onabit of a road trip this weekend and found a mill that could provide a 30 ft. 7X7 but it's not free of heartwood. I'm pretty sure that masts on Nanoose are simply trees. It it necessary to avoid all heart wood?

Also, it would probably be a year before the stick would air-dry but I found out there's a place down the road that would kiln dry it. Appparently they start with humidifying it first to get a controlled amount of moisture then dry from there. Do I run the risk of causing the timber to warp or check excessively if it's kiln dried?

If I do decide to go with a solid stick, am I better off just scarphing two smaller sticks?

Fwiw...the timber would be about $200 from the mill...

Dave

[George Ray]

You seem ideally located for good spar stock?

Sitka spruce is native to the Pacific Coast region from southern Alaska (Kodiak Island and Cook Inlet) , southeast through southeastern Alaska, western British Columbia, western Washington, western Oregon and northwestern California.

http://www2.fpl.fs.fed.us/techsheets/SoftwoodNA/htmlDocs/piceasitchen.html

[Jay Greer]

You may wish to consider a thick walled hollow glue up spar if the mast is to be "heart free". This is a good way to avoid checking and rot. A core box bit or plane can be run down the center of the two halves prior to final glue up thereby creating a slight hollow down the middle. This will lessen the potential of checking by allowing some room for expansion and contraction of the grain as well as room for wires, if desired.
JG

[SV Papillon]

We are in a similar search for our boat. I recived the following recommendations for spar builders in Port Townsend of of a post on spartalk.


Steve Chapin of Point Hudson Boat Shop, 360-385-6863, who just built a birdsmouth foremast for the pinky schooner Pleiades.

Bruce Tipton, 360-437-9342, excellent traditional sparbuilder, also in Point Hudson

Haven Boatworks, 360-385-5727, or the Port Townsend Shipwright's Co-op, 360-385-6138

Good luck,

Jake

[Bruce Hooke]

We went onabit of a road trip this weekend and found a mill that could provide a 30 ft. 7X7 but it's not free of heartwood. I'm pretty sure that masts on Nanoose are simply trees. It it necessary to avoid all heart wood?

It is certainly possible there is something I don't know here...I make no claims to being especially knowledgeable about building spars...but I don't see why it would be necessary to avoid any heartwood. What you do want to avoid is any of the pith of the tree or the wood with a few growth rings of the pith. If the pith is included in the piece of wood, which, of course, it always is if the mast is made pretty much straight from a tree, then the mast WILL check. This is not a maybe, it a given. Trees shrink more around than they do in and out, so timbers that include the pith always check as they dry. How much they check depends on how deep the pith is into the timber. The deeper it is, the bigger the checks.

On drying -- a solid piece of wood 7" thick will not dry in any reasonably amount of time, so large solid timbers are almost always worked relatively green. As long as you plan for a bit of shrinkage over time this should not be a big deal.

I'd be a bit cautious about kiln drying a piece that thick. The proper drying schedule for a 7x7 is going to be a bit different from the drying schedule for a bunch of 2" thick boards, and I have to assume that your mast would be in the kiln with a bunch of other wood, most likely of much smaller dimensions.

[Paul Stohlman]

A solid spar can be a smaller diameter than a hollow one of the same strength. The percent of increase is covered in Skene's Elements of Yacht Design (for example). Your mast partners will limit the max diameter, but I've not (yet) seen that become a real problem.

A heavy spar will give the boat a different motion than a lighter weight one. The change from solid to hollow wood would be less than solid wood to carbon fiber. A bit lighter, but stiffer, is a good compromise.

The magic of birdsmouth construction is that it is so bloody simple, and has a greater glue surface.

It is satisfying, though, to take a tree, make it square, then eight, then sixteen...all the way back to round.

[Nanoose]

Jake, if we go with a hollow spar, and decide to have one built rather than do it ourselves it's nice to know we've got some options. I'm not sure if I can figure out the cost of getting a.) the mast here or b.) the boat there outweighs having it done locally though...

Bruce/Jay/Paul: Thanks for the info on construction and wood. I didn't know why wood checked, I think I understand more now.

I'm pretty sure that I can have a laminated timber made up of 4X4's which should be free of heartwood and I think I should be able to have it hollowed before it goes together.

Dave