View Full Version : Whitehall mast dimensions

07-14-2001, 08:10 PM
I have built a 17 ft 6 inches Whitehall broadly to Gardner's lines, but strip built overlaid with epoxy, and the deadrise at 10 degrees rather than his 15, since my boat will be around 75 lbs lighter than the traditional Boston one (i.e. less than 200 lbs all up). I propose to row if I have to go dead up wind, and sail across and down (effective beating not needed). I have given the boat a 2" keel strip, which over an effective 16 ft gives say 2.5 sq ft, about the same as a small dagger board. The rudder adds another square foot. I will add a lee board later if it turns out to be needed. My sail is a high peaked loose foot lug, re-cut from an old 80 sq ft dinghy sail - it comes to about 60 sq ft. The mast is 13 ft overall, and I would like it to be free standing held in a gate 20 inches from the base.

Here's my question. Other than by guess and by God, or cut and try to be more accurate, how does a person settle on the mast dimensions? What I am proposing to do is to epoxy two spruce 2x4x13 ft together, leave them "as is" the first three ft, then taper evenly up to the head, where it will be 1.5" by 3". The whole thing above the lower 3' will be nicely (I hope) rounded, becoming oval at the head.

Given that the total cost of materials is $50 (Canadian), there does not seem to be too much to gain by intensive theoretical calculations, but does anyone have some good practical experience to suggest if anything in this approach is not likely to work? Additionally, is this mast overbuilt for the job? I would very much like to get it to a reasonable minimum weight.

Thanks for any interest!


Mike Field
07-14-2001, 10:02 PM
Tony, I think perhaps the mast might be a bit over-dimensioned the way you've described it.

As I understand it, you're planning on leaving it square until a foot or so above the partners, transitioning to a circle for most of the height above that, but then transitioning again to an ellipse for the last foot or so. Is that right?

The shape sounds fine, but I think you could get away with an overall dimension of 2 3/4" rather than 4", which would save a bit of unnecessary weight. (You could probably go to 2 1/4" if you were going to stay the mast.) And then you could run the gradual taper to about 2" at the top.

I wouldn't ellipsise the mast, though, until clear of the halyard sheave. It can be a dumb sheave without any problems, but it should run athwartships, not fore-and-aft, and you don't want to be cutting too much timber away just there. You can essentially do whatever you like once you're properly clear of the sheave, though -- carve a dolphin up there if you want.

I wouldn't bother about trying to build the mast hollow. I think in a boat this size that's overkill. But if you wanted to save the little extra weight that would be available, yuo could rout channels inside the two laminations before gluing up. (Don't take out more than the middle 1/3 of the finished mast, though, or it will be too weak. And if you wanted to get a really good hollow mast, you could always search the forum for details on the birdsmouth technique.)

When gluing up the laminations, don't forget to align the two pieces with the grain running in opposite directions first.

Final comment regarding keel area -- the underwater effectiveness for reducing leeway depends more on the depth than on the length immersed. The total area can actually be less, if it goes deeper. I suspect you'll find that the leeboards will be necessary except when running. It's worthwhile thinking about upwind performance too, anyway, as trying to row upwind with the sail up and rigged is really a bit of a bugger (and probably worse with less deadrise, as well.)

Hope this helps, and I'm sure there'll be other views to consider as well.

07-15-2001, 04:30 PM
To Mike Field.

Thanks for your thoughtful reply. Very dangerous, since I've taken your advice (more or less, anyway), and now have someone to blame if things go wrong. Splendid - or it would be if you didn't live on the other side of the world, so that I can't get at you!

The mast took a full day's work to complete from the glued up rough stock stage to ready-to-varnish, which seems excessive. A cold beer is going down well.

I made the base 3" by 3 3/8", and shortened it to 24" from the planned 36", when the taper starts. The 3" dimension tapers to 2 5/8" at the top, and the 3 3/8" to 1 3/4" ditto. Edges are strongly rounded, but it still remains obviously a rounded rectangle, rather than a turned section.

The wider dimension at the top goes athwartships, of course.

Weight as made is 20 lbs by the bathroom scales, and the mast is quite easy to handle (raise in the boat) since the bulk is in the lower portion. Given that the wood is a bit more knotty than I would have liked, I have left around 1/2" more than is probably necessary. I suspect that one could shave 5 pounds off without much risk, with better quality clear spruce or similar wood.

All I have left to do is paint the inside, and assuming the paint dries, launch date should be next week. I don't expect that either the sail or the new oars on order will be ready, but that's too bad!

Your comments on sideways resistance (length Vs depth) were interesting. I will try the boat out as built, but I fully expect that the next project will be lee boards. Should be fun.

Regards, Tony.

Mike Field
07-15-2001, 06:35 PM
Crikey, that was quick! Let us know how you go, Tony, won't you -- preferably with photos?

Phil Young
07-15-2001, 10:20 PM
I'd probably bow to Mike's opinion as a rule. But I have an oughtred acorn skiff which is a 12' clinker ply whitehall. It has an unstayed mast. I'm guessing, because I'm at work and its at home, but I'd say its mast at the partners is about 3". Its round all the way and tapers to about 1 1/12" at the top. The dumb sheave is fore and aft. I'd be concerned about an oval shape with the large dimension sideways. Seems to me a lot of the strain is fore and aft, particularly when close hauled, but then with that little keel strip and no c/b, you won't be doing that anyway!!

07-16-2001, 06:07 PM
Thanks for your responses, Mike and Phil.

I have re-cut the base to a 3" square, and really shaved and rounded the corners of the taper all the way to the top. The final weight is 18 Lbs, down another two from yesterday. With a coat of paint, it looks pretty nice - or at least it no longer looks like glued up construction lumber, which is how it started out.

I agree that the oval dimension should be fore and aft. I am making the mast step so that the foot can be adjusted fore and aft, to let me play with different rake angles. Any thoughts in this area?

I think that my preference runs to a small block at the top, rather than a dumb sheave. It is only a little additional complexity, after all. A strop with parrell (sp??) beads should hold the yard to the mast, I hope.

To be continued!

Regards, Tony.

Phil Young
07-16-2001, 06:47 PM
Hmm 3" square is going to be less wood than 3" round. But mine seems plenty strong. Its made, by the way of a single piece of what we call Oregon Pine in Australia. Used to be a common construction timber years ago. It fits in the boat, so I guess its around 11' long. I don't have anything holding the yard to the mast. Halyard tension does that well enough, and its pretty close to the sheave when fully raised. Even reefed its not been a problem. I suppose you'd have a bit more control when hoisting and lowering with something there, but the sail really isn't big enough for that to be much of an issue. I prefer to keep it as simple as possible, to get off the triler and sailing as quickly as possible. Good luck, keep us posted.

Phil Young
07-16-2001, 06:49 PM
Actually thats wrong isn't it. You've got more wood than me. Note to self. Put brain in gear, and coffee in system before posting.

Mike Field
07-19-2001, 07:17 AM
Sorry for this late reply, Tony. All my bb time has been taken the last few days in exhuming, inspecting, and then reburying some colonial skeletons, as perhaps you've seen.

I was glad to see Phil's last two posts, though (especially the last one, as I thought he'd lost it there for a minute....

Now, I know you've finished fabrication, but in case you decide later that you haven't, quite, I definitely wouldn't be going any smaller with the mast. In fact, I'm not at all sure that that taper hasn't gone a bit too far already at the top. I guess it'll be okay, but neverthess I'd be inclined to load it up pretty gently at first, till it proves itself.

As with Phil's, my boat's mast is solid oregon too (aka Douglas fir.) (It's what we use because we can't get sitka spruce or a Norway pole.)

A dumb sheave will work fine for the main halyard, but if you wanted to put a little bronze sheave in there, you'd be doing no more than I did with Aileen Louisa. And as Phil says, you shouldn't need anything in the way of a parrel.

Is this a standing lug? And tell us about the yard you'll be using.

By the way, to do it all in one day I think is pretty good going -- you're definitely not in hairshirt territory on account of that.

07-19-2001, 11:59 AM
Well if Mike has to take the rap I will be there to share it -- actually the design you guys came up with I have float tested without problems for 20 years in a 16' Whitehall stretched from Howard Chappelle's Small Sailing Craft, p. 176 I believe (his plan is 14'). My mast is unstayed, 13' total, 3" square for first 2' to partner, with tenon at the keel, round above partner, tapering to 2" dia at top. Dumb sheave fore and aft. Two glued pieces of solid Doug Fir, which probably makes it heavier than spruce would be. Mine is a loose footed sprit rig (sprit is spruce), and I have found that I don't use the halliard that much -- to douse the sail I just pop the sprit out of it and brail it around the mast -- much quicker, and more out of the way than in the boat unless there is so much wind that you want to get the mast down too. I have had the reassuring sensation of increased seaworthiness in a blow as soon as the mast comes down. My Angeline has a centerboard, probably 15"x36", which improves her windard sailing noticeably.

I would agree with Mike that this rig is a bit over dimensioned, but it has held up. Also would agree with him that rowing upwind with the sail up is a bugger. Brailed around mast presents some extra windage, but I live with it or get the whole rig down -- it fits pretty out of the way with 2' of mast butt hanging over the stem.

The original construction, changed before the sails were cut, was another 15" of mast. That would have made about 120 sq ft of sail, and I thought it would make the boat too tender for what I wanted to do with her. It was a good choice. I've never played with the rake -- she has only the slightest. Weather helm is about right.

Yes do tell us how it works out!!

07-19-2001, 07:37 PM
Thanks for joining us, Pwilling. Your experience is encouraging. Looks like so far so good.

The next question is the yard dimensions, and here is another real mystery. What I have told the sailmaker who is re-cutting the old (and free!!) dinghy sail is to assume eleven feet of useable mast, and an eight foot yard. He is going to get as much completed sail out of the original 18' luff by 8'6" foot as possible. We are, therefore, starting with a very high peaked sail, on the theory that we can always cut at a lower angle later, but can't as easily add.

I have in mind 3' of yard below the point of suspension, and 5' above it. Should the yard be a simple pole (say 1.5" by 2", heavily rounded corners)? Or should it be thicker in the middle, at the suspension point, or what??

I promise not to begin until after the weekend to give anyone interested a kick at the can. The goal is the same as the mast - adequately strong, but not too much over dimensioned. Spruce is the material. I sail in inland water (New Brunswick's Saint John river system) which includes several large lakes, but never more than a couple of miles from shore (usually much less) so failure/breakage of a part is not catastrophic.

Regards, Tony.

PS. The paint is drying nicely, now the weather has warmed up, and the oars have come; 9' clear spruce, straight blade. Target launch date Wednesday next.

Mike Field
07-19-2001, 08:42 PM
I hate to repeat myself, but --

Originally posted by Mike Field:
Is this a standing lug?

(It matters.) Do you happen to have a sketch you can post?

Nice to hear, too, about Pwilling's two decades of confirmatory experience.

Phil Young
07-19-2001, 09:41 PM
My yard is a bit longer than that, I'd say about 9 or 10 feet. It's no more than 2" thick, maybe a little less, and tapers a little toward the ends. Its round. I just tie the halyard on with a clove hitch and a couple of half hitches to be sure. I suppose about 2 or 2 1/2 feet back along its length. It bends a bit, particularly if I don't bother lacing the head, but its never broken. It sets with quite a high peak. I should get the thing out of the shed and measure it for you. It was designed for the 15' version of the Acorn, I thought the sail for the 11' version looked a bit small, so with Oughtred's approval I went for the larger sail. Moved the CB forward one station, and made a kick up rudder instead of his fixed blade, it all works great. I had to rig it with a boom because with the bigger sail i didn't have the sheeting angle for a loose foot.

07-20-2001, 05:51 AM
Sorry, Mike. Yes, it's designed to be a standing lug with brails, a bit like a toy version of the naval whalers I sailed in some 40 years ago (I have no idea whether such things still exist nowadays). Actually, one could attach the tack well forward of the mast and turn it into a dipping lug, I suppose. That would drop the angle of the yard, and have other interesting effects. Sounds like a future experiment.

The main problem with a very high peaked standing lug with a boomless foot will probably be twist down wind; the head will tend to sag off. One of the benefits over a spritsail (which was tempting, except I have never even seen one) is the ease of either brailing up, or of dropping the whole sail c/w yard by unhitching the halliard. The spritsail is squarer downwind and has a lower c/e. There seem to be pros and cons of everything, don't there? The standing lug with loose foot was the final choice because of its general simplicity for sail training (grandchildren and sea cadets), and the ease of going from sail to oar and back in variable conditions, common around here.

Incidentally, I have lots of buoyancy under the seats. It ought to be possible to cope with a capsize, although whether one person could actually right a swamped boat of this size and weight seems doubtful. Yet another experiment for a summer day?

Regards, Tony.

Mike Field
07-23-2001, 04:44 AM
Another apology for a late reply, Tony -- sorry.

Another question -- when you say the sail is loose-footed, do you also mean boomless?

So here's the next question. Instead of a dipping lug, why not a balanced one? Similar, although perhaps less sail forward of the mast, but with no need to dip it at all?

If there isn't a boom, and given the high peak and possibility for sail twist, is it too late to bring the tack forward a bit and make it fast to the keelson or the stem, turning the whole affair into a balanced lug? The balance area should help support the yard and relieve the twist. And if there is a boom, you could do the same thing by allowing it to project forward of the mast while holding the forward end back to the mast with a tackline. (This would save you having to worry about fitting a gooseneck or jaws, too.)

Like Phil, I would think your yard could be reasonably narrow. Traditionally it would be hooked on an iron traveller that ran up the mast at the end of the halyard. In my kayak I put a permanent hook on the yard, and an eye-splice on the end of the halyard, which worked quite well. I see that Phil simply ties off with a clove hitch, which clearly works okay for him. (Or you could go a bit more trad and use a topsail halyard bend, I suppose.)

By the way, my yard is only about " square -- but then the sail it's carrying is only about 10 sq ft.

[This message has been edited by Mike Field (edited 07-23-2001).]

07-23-2001, 12:59 PM
Mike - yes, a boomless, loose-footed standing lug. I have a small deck over the bow, the first 4' 6", roughly to where the first thwart would normally be. This lets me secure the tack anywhere between the mast and the bow. It's just a matter of adding an appropriate fixture in the chosen spot.

It seems to me that the difference between a dipping lug and a balanced lug (both boomless) is really a matter of degree, not kind. With a balanced lug, one does not dip, and the tack is (much) closer to the mast. With the setup I have, I really have them either one or the other at will, just by changing the tack position. With a boomless sail, would a balanced lug (tack a foot or so forward of the mast) be any better than a standing lug (tack close to the mast), and if so, why?

As of a week or so when the sail comes, I should be able to find out.

So far as the yard goes, after reading about the experience of others, I think I will start with a tapered oval, 1.5" by 2" at the suspension point, reducing to 1.25" round at both ends. It sounds as if this will be plenty strong enough, and not too heavy.

Regards, Tony.

Mike Field
07-23-2001, 07:39 PM
Tony, I've never sailed with a dipping lug, but they're supposed to be the most effective. (The zulus had them, and apparently went like the wind.) Because you dipped, theyard was always to leeward of the mast, so the airflow along the sail wasn't disturbed. (And if you decide to rig this way, you're supposed to dip forward of the mast, not abaft it.)

The balanced lug isn't as effective because, as a sprit does, the yard cuts across the sail on one tack. But I suspect the effect isn't all that great. If you were racing you'd want the little bit of extra performance, I suppose, but I myself have never been able to tell the difference from tack to tack, either with the lug on my kayak or the sprit on Aileen Louisa.

But the point about the balance area (that part of the sail foreward of the mast) is that it's larger with the balanced rig than with the standing rig. So the wind pressure on the forward part of the sail works (on the sail itself) to balance that on the after part, thus reducing twist. (The dipping lug does this even more so, of course, and I daresay that contributes to its better performance, too. I'm just not sure whether going to that extreme is worth the bother, though.)

07-24-2001, 11:46 AM
Well Tony as long as you brought it up, I'll
take the bait on the swamping issue. I have swamped my 16' Whitehall three times, and gulped a good greenie a few more times than that. The first swamping was on purpose, in a warm lake with no wind -- to see what would/could happen. She floated upright, awash, with me in her, and I could bail her out. The second time I had a green sailor who shipped the tiller OVER the traveller rope, I didn't notice it, the wind lifted the rudder out, we broached, and slurped her full in a blink. Then I sat there with cold salt chuck up to my belly button, saying, yes, where is that ^&$$#*( bailer anyway?? Not finding it, I zipped a beautiful Norwegian fender in half and handed one half to my cadet and started bailing with the other. We had her dried out before anybody could get to us. The third time we tried to run some surf onto a beach, and didn't make it. A mess (and another story which by the way made the Navy look pretty bad . . .)

The first time was the most important -- I highly recommend it. That boat is pretty beamy and flat in the floors, which makes her want to float upright -- good to know what yours wants to do when she's awash.