Alberg interview

[Bill]

The following is a portion of a 1978 interview of Carl Alberg (77 at the time) where the discussion of boat design slides into a bit on mast tuning and sail trim. (A photocopy of the typewritten interview was provided by Peter Theis, A-82 SOLSKEN.)

>>>>>
Q = Jim Priestly, Massachusetts Bay Typhoon Association
A = Carl Alberg, Navel Architect
>>>>>

Q. I am not much of a mathematician, and I don't know all the particulars about designing but I think it is interesting that you chose that particular length and that particular shape and the fact that it has a 900 lb. keel and it is stiff. What happens when you sit down a drafting board and say "I want to make a boat for this man to do a certain job?" How do you come up with these ideas?

A. Well, of course, he tells me what he wants and I decide that the boat should have so much beam and so much draft and freeboard and displacement. I determine displacement. I calculate the balance so that you have stability and I calculate the mid section. I use coefficients, the mid-section coefficient, and take it from there and by trial and error you arrive at the displacement you want and then you have to determine the amount of lead you want. You have got to estimate the weight of the hull and rigging and everything inside. Then of course the sails. You have to balance off against the displacement.

Q. The righting arm?

A. Yes, so that you have the stability you want. You can take out of displacement, the cubic ft. and compare it with the square root of the sail urea and come out with a figure like 4, say 3.9 or 4.1 or 4.2, in that area, and that gives you just about what you want, depending upon what you want to use the boat for, and where you want to sail. If you are sai1inq in Marble Head Bay you don't need as much sail area as you do on Long Island Sound, for instance.

Q. Because of the winds?

A. Yes. The Typhoon worked out pretty well. I can only remember reefing the mainsail once. It was a real screaming Norwester and everything was laid out flat and I rolled about four feet on the main and she stood up like a church.

Q. I had run one time below Plymouth, it was to the Cape Cod Canal in about six foot seas

A. That's a mean area.

Q.... and I just had the jib up and whether I did not have the boat tuned up correctly or not (it was a broad reach, almost 1ike a run) I found that I couldn't control the boat as well with just the main. Could that have been the reason?

A. If you had a full main I would say you would have a bad weather helm; with a reefed main, you might be better off.

Q. I see. The Dealer that sold me my boat said that the mast should be absolutely perpendicular. Do you rake it aft?

A. I start with a pretty good rake aft-about 3 or 4 degrees, if I find that I need less weather helm I rake it more forward. But, I have never had it perpendicular; it was always raked a ft.

Q. A little bit aft? I wi11 have to try that then.

A. Where the helm is, it a ll depends on how much the boat is heeling over. If you keep the boat absolutely level you will have no helm; when she starts to heel she picks up weather helm, and if it heels well down she has a bad weather helm. That happens on every boat. I have had people write to me and say, "I drive the boat and she has a bad weather helm,” and I said "don't drive it with the rail under water. Drop the main and sail with the jib. Cut it down."

Q. I went by a fellow in Quincy one time going the opposite direction that I was headed. .He had a terrible weather helm on his boat and he didn't know what was wrong. (having an un-reefed main up?) That's bad.

A. It's worse than that; that's dangerous.

Q. He said that was the way the dealer had set it up for him. (vertical mast?) It was a shame.

[ebb]

[and I thought a mast rake was an implement for gathering falling luffs in freshening winds]


How is Peter Theis doing these days? Back to sailing? Miss his posts.


Very interesting interview - with an absolute bomb of an admission by Alberg - "I start with a pretty good rake aft, about 3 or 4 degrees - if I find that I need less weatherhelm I rake it more forward. But I have never had it perpendicular - it was always raked aft."
The master 'sees' his vessel sailing as he puts lines on paper.
Weather helm has been a subject on these pages.

I know mast rake is not something we do when sailing. Can't imagine really that it can be done Sunday morning in the marina - maybe.
The boat would have to be set up with the mast and luff dead straight. And the mast heel set with a shim.
Not with a bend introduced into the mast by tensioning the backstay (and untensioning the forward lowers and the forestay.)

Have three scale enlargements of the Ariel sailplan (pg148) from the Manual.
Using them to measure is probably inaccurate as copy is made from a very small drawing:

Square off the waterline and straight edge at 90 degrees shows a 4" AFT RAKE at the top of the Ariel spar.
[It's 6" aft on another drawing from the Manual.]
Less than 1/2 a degree.
But it's hard to say how accurate that is.
The drawing itself is a redraw by a J.L.Lee (not Alberg.) The rendition has some striking inaccuracies
- but that's what we have.

A 3 degree rake from vertical would put the mast 13" aft at the top.
Pretty radical wouldn't you say?
Wonder if the boom could be brought up to horizontal (viz the gooseneck?)


Alberg: "......everything was laid out flat and I rolled about four feet on the main and she stood up like a church.":D

[Bill]

Ebb, the boat under discussion is the Typhoon, which is only 20 ft LOA. Relatively light mast, so you can probably “rake” it back with little difficulty. (See the Cape Dory Typhoon Owner’s Assn at: http://www.capedory.org/specs/typhoon.htm)

The same thing can be accomplished in the AC yachts mostly by “bending” the mast aft to spill the air from the over powering main in strong wind situations.

BTW - Alberg’s statement, “That happens on every boat,” is directed to all of his designs, not all sailboats.

[ebb]

So how do we go about bending the mast?
There must be a drill.

What happens to the set of the sail?

Would bending the A/C mast relate to the Typhoon discussion.....
Any racers doing this on the Bay, tweeking Harken wheels built into the backstay?
Do they do it for other than weather helm?

Could an A/C mast be actually bent back 12"?
Ooops, there goes the sheave bolt, or was that the beam under the mast step?
Isn't something going to break if the mast is suddenly straightened?
Cunningham, halyard, backstay?


But I can see how this relates to an A/C rigged with a more permanent straight mast rake. Or not!
And how aware Alberg is approaching the problem.

Could be important for litlgull whose balance may have altered with her many unauthorized revisions!
Or boats who have gained heavier hulls and gear changes over years spent on the water.

Noticed that the natural sag of the mast in my driveway
- horizontally suspended on its long axis between two sawhorses -
is barely one inch! Pretty stiff mast.

[Ed Ekers]

Hi Ebb, Thought I would add my two cents on this. I think you first have to look at rake vs. bend. The master speaks of rake. This is easily accomplished with tuning. I agree the rig is stiff but you can achieve a small amount if bend from the spreaders up. For years I have tuned Pathfinder with as much mast rake as possible. Head stay is original design measurement and then backed off the turnbuckle to show just full thread at both ends. Then would tighten our adjustable back stay to create appropriate tension on head stay. This set up would result in significant mast rake. (at least four inches and maybe more) If we were racing on the bay in what I would expect to be heavy breeze I could still tension the back stay some more and that would result in a small amount of bend at the spreaders up. I doubt I could get four inches but I would guess two to three inches. The head and back stays were always set first and then the shrouds were adjusted to support the set up. Just a side note whenever we come in to dock I always back off the back stay adjuster so she does not sit there with her panties all bunched up.

As far as the effect of sail shape all this adjusting would change the sail set but we would just make adjustments to create proper trim. Hope this offers a little more clarity.

[ebb]

Ed, Certainly know your cents are like collectible Lincoln 'wheats' from the twenties!
Wonderful stuff.
Couldn't have imagined bending the mast from the spreader UP! That's amaxing.

And I not sure what that MIGHT be doing except to help cancel possible weather helm in stiff wind.
But there also must be some benefit in the set of the sail. What...? a better foil shape to
the top half?

Thanks for the how to ! ! !

:DWish we had that Monograph from you on 'How To Get The Most Out Of Sailing Your Ariel.'


I think you would approve of setting the mast up with the DESIGNED RAKE found in the sail diagram in the Manual.
Water line is datum. But the boom is also drawn horizontal with the waterline.
My guesstamate is 1/2degree. Imco I'm taking it off a questionable redrawing of an original Alberg.
What is your guess? Of course I'm sure you don't guess on that score.
So should I ask how much rake in the mast you have in Pathfinder's racing set up?
That is: Befor you tweek the top half of the spar......

[ebb]

[sorry about the strange repeat here]

Ed, Certainly know your cents are like collectible Lincoln 'wheats' from the twenties!
Wonderful stuff.
Couldn't have imagined bending the mast from the spreader UP! That's amazing.

And I not sure what that MIGHT be doing except to help cancel possible weather helm in stiff wind.
But there also must be some benefit in the set of the sail. What...? a better foil shape to
the top half?

Thanks for the how to ! ! !

:DWish we had a Monograph from you on 'How To Get The Most Out Of Sailing Your Ariel.'



Alberg: "I start with a good rake of 3 to 4 degrees.......I've never had it perpendiclar....."

[Ed Ekers]

Ebb, you’re correct both the rake and small amount of bend does change the sail set. What they will do is open up the leech of the sail to allow wind to be forced out easier. This in turn will allow her to set upright easier (on her lines) and as the master says the more upright she sails the less helm you will experience. Also I have mentioned before if you are dealing with a heavy helm you could try to travel up and then sheet out on the main. This also will allow her to sit more upright and you will just be driving forward off the lower section of the main.

I suppose a separate point to adding tension to the back stay, it puts a tighter load on the head stay. You could also do this with the jib halyard but the tighter head stay will reduce the amount of sag. Together this will move the effort forward and allow for a higher point of sail which again helps put her on her lines, hence less helm=equals less drag.

Now I am just getting carried away and it doesn’t mean a thing in the big picture if you are just trying to enjoy the ride to the south pacific……..ed

[Ariel 109]

Don't forget the mainsail outhaul. Getting it really tight can have a very positive effect on sail shape and boat performance. This especially works with older blown out sails which often are plagued by too tight of a leech, try it even in light air.

[ebb]

Great stuff!

ED also began a thread awhile back titled
'Adjustable Backstay'

Well worth visiting for it's photo collection.




Ed what did you finally install?
__________________________________________________ __________________________________________________ ________
From the South Pacific point of view, I like the tidy and laidback adjustable 'solent stay' type turnbuckle.
litlgull A338 has to have a split stay with plates on the corners - and a disconnect at boom height for forward mast lowering.
A 'traditional' three-point triangle plate couldn't work with an adjustable single turnbuckle. (unless it was placed above the divider plate!)
Don't know that the multi-block system is robust enough to be permanently rigged on a cruiser version of Ariel. ? ?

[Ed Ekers]

Because we dropped the heavy racing schedule we stayed with the same unit as Scott. We do participate in a few fun races here in Santa Cruz so we will make adjustments as described earlier but are no longer concerned with adjusting on the fly. I guess it is more for head stay adjustments.........ed