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Sep 10, 2009, 09:52 PM
Damp and Dizzy member
Brooks's Avatar
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Photos of brig conversion


Here are a couple photos of the brig conversion. I'll sail tomorrow if the wind cooperates, and hopefully obtain some on-the-water shots. The Aldebaran has now sailed as a fore&main topsail schooner, a brigantine, and a brig.

btw, it was relatively common for a hull to support several rigs over it's lifespan. The owner might have a new job for the ship, and a different rig might be preferable. You can see the topsail schooner heritage in my model's sail shapes and yard spacing. Remembering that ships were first and foremost economic enterprizes, one can understand a frugal owner salvaging as much as possible from the previous rig.

Single masted ships might become schooners, and vice versa. For example, the Emma C. Berry (modeled by Sterling many years ago) worked as a sloop, then a schooner; she was converted to make her easier to handle with a small crew. Changing from 1 mast to 2 would seem to be the going the opposite direction, but spilting the sail area over 2 masts instead of 1 would mean less sail weight per mast to hoist aloft. Small work boats changed rigs seasonally: the New Haven oyster sharpie would sail as a 2 masted ketch in the summer, and as a single masted sloop in the winter. The sharpies had 3 maststeps for this purpose.

Oops, I meant this to be a posting on the topsail schooner thread, but I hit the wrong button, sorry.

Berry info:
http://www.windjam.com/emmacberry/index.html
Last edited by Brooks; Sep 10, 2009 at 10:00 PM.
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Sep 11, 2009, 05:37 AM
Diver-driver
meatbomber's Avatar
Looks awesome can`t wait to hear how she sails with this Rig !
One thing i have wondered about is the high mast rake angle, can you explain why they used such a high rake angle ?
Sep 11, 2009, 06:23 AM
Damp and Dizzy member
Brooks's Avatar
Thread OP
Mast rake aft: I have never read a good explanation for the rake. Reasons given have been: a) helps poorly cut sails set better (unlikely, in my opinion, bags stay bags whichever way you hold them).
b) looks fast, just cosmetic (possibly, but the sea don't care about looks; appearance was important, however, and skippers of the era were probably just as fad concious as skippers of today. It does look fast :-).

My own experience has found one positive feature of mast rake: The Aldebaran does not change summation CE with sail changes as much as the no-rake Pamir. One thing I realized is that the rake on the Foremast mimimizes CE changes as you add sails from bottom to top (the normal sequence of adding sail area as the wind drops). In a no rake mast, each sail added to the Foremast moves the summation CE forward. But with rake, the new sail's CE is positioned closer to the old summation CE than it would have been if the mast were un-raked. Thus, you can add sails to the Foremast and not develop excessive lee helm.

For the Main mast, the situation would be reversed: adding square sails would move the CE further aft (developing weather helm). Most post-1860's topsail schooners dispensed with the squaresails above the mainsail, however, so this "bad" effect of Mainmast rake would not be a factor. The replacement fore&aft gaff topsail would not generate as much weather helm as the squares it replaced simply because it is a much smaller sail. I've never read an explanation for this change in the rig of the post 1860's topsail schooner mainmast...but I may have discovered it:

I think one reason they dropped the main squares (and substituted the triangular gaff topsail) is that the main squares backwind easily on a beat. The wind is deflected off the foremast squares ("downwash" to an aviator) and hits the main squares. The effect is to "back the wind", making the main squares think the wind has shifted to the worse. So to keep the main squares full, you have to fall off a few more degrees than you'd steer normally on a beat. This wind deflection happens to all multimasted ships, square-rigged or fore&aft. But since fore&aft sails can be sheeted tighter to the centerline, it's easier to adjust aft masts/booms/sails for the deflection.

If you were needing to maximize performance to windward, the main squares of a topsail schooner might be better off furled: it would depend on your hull speed vs angle made good to the wind. The sails undoubtedly increase hull speed, and whether the increase would make up for the lower pointing angle is something only experience would discover.

Chapelle makes the point that obscession with performance to windward is partly an artifact of racing boats. The normal race course emphasizes windward work. The leg o' mutton sail (now called Bermuda rig) does well going to windward, and thus dominates racing and cruising boats today. But it's not a good rig for other points of sailing; look at the multiple jibs and spinnakers carried by Bermuda rig racers today to remedy the ineffectiveness of the leg o' mutton main. It's also useless for maneverablilty, compared to squaresails.

In real Pyrate vs Merchant races, the Merchant would not beat to get away. Rather the skipper would put the ship on the her best point of sailing and try to sail the pursuer under the horizon. Of course if beating was the best point, then the Merchant would set that course. But on the open ocean, the better way was to disappear quickly, not slog to windward, in sight of the Pyrate, and at risk of a drift down to his position if any Merchant gear should carry away.

So. to summarize, on the Foremast, rake aft has a very positive effect on helm as you change sails. The possible negative helm effects of Mainmast rake disappeared, for topsail schooners, after the 1860's. Choice of sail carried on the mainmast during a beat might have also minimized helm effects resulting from the aft rake.
Last edited by Brooks; Sep 11, 2009 at 06:32 AM.
Sep 11, 2009, 04:34 PM
Registered User
Many Thanks for a very clear explanation.
Sep 11, 2009, 04:53 PM
Diver-driver
meatbomber's Avatar
Yea Thanks Brooks! Your threads and are by far the most educational ones that`s for sure

i`m right now dreaming of a Footy Brigantine.. but i have to readup on CLR and CE calculations in your other threads and the setup of the Brace Servo arm / F&A sail sheets..
Might not be a footy according toall rules tho
Sep 11, 2009, 06:17 PM
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Brooks's Avatar
Thread OP
Both ships look very nice, MB :-). I needed much more fin for my bottle topsail schooner (hull footie length) than the thin chord fin you show (and most Footies use).
--------
The CE vs CLR calc can be as simple as you want to make it. Simple: a)visually guess at the center of area of the sails on the foremast and draw a dot on the paper, ditto the main mast sails.
b) draw a line between the 2 dots. The summation CE is somewhere along that line. c) If the sail areas for both masts are equal, then the middle of the line is the summation CE. If the foremast sails have 2x the area as the mainmast sails, then the CE is closer to the foremast, at about 1/3 distance aft of the foremast's dot.

CLR can be found the same way, guessing at the center of area of whatever is below water.

If the CLR is aft of the CE, then the ship will want to turn downwind, ie leehelm. And vice versa for weather helm. Think of the CLR as the pivot point of a weathervane, with the CE as the feather of the weather vane.

I don't worry about the CLR much, since I make all my boats with a fin keel that can be bolted on at several places along the hull. That way I can adjust the CLR to line up with the CE. I let the ship tell me if the fin is too far aft or not when she sails. Good idea to test this at a part of the pond with an on-shore wind, so that if you misjudge keel location greatly, the ship will drift back to shore, not out to sea :-).

------
Refinements: The CE actually is forward from the geometric center of the sail, just like wing lift is forward from the center of the chord of a wing. Ditto the CLR, since the hull and fin work together like a wing in water. The CLR will move forward as the ship gathers way; when the ship is stopped, the CLR is at the geometric center, but as the ship starts to move, the lift, ie CLR moves forward. A pretty good guess of the final postion of the CLR is at the 1/4 chord point, just like for a wing.
Sep 11, 2009, 07:19 PM
Diver-driver
meatbomber's Avatar
Thanks for the explanation... i`ll have to take a while to digest that... i think tho that the trial and error will be my method so moveable keel it will be.
Sep 12, 2009, 08:41 AM
Back in the game.
Yellow Baron's Avatar
Looks good MB! I like the topsail schooner the best (but then again I'm biased ).
Sep 13, 2009, 02:24 PM
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Brooks's Avatar
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Chapelle on Mast Rake


"The Baltimore Clipper, it's origin and development", Howard Chapelle, 1930, page 169. <plus my comments relative to Aldebaran>.

"Much has been written in the past about the raking masts of these craft. Probably no other reason for the extreme rake of their masts was considered other than custom. The position of the spars so far forward made rake of importance in the sharper vessels in overcoming pitching and diving. <sharper vessels: those with a very pointed bow, and thus less buoyancy forward than blunt-bowed vessels>...The rake of the masts also aided rigging the craft, and perhaps explains the light rigging so common in the Baltimore Clipper. < Aldebaran backstays have a very good lead from the deck to the raking masts, so their effectiveness is enhanced, and small diameter line suffices> Rake of masts was rather extreme up to 1858, afterwhich it was reduced until masts became nearly plumb. We are now beginning to see the rake again introduced <1930>. Undoubtedly raking masts have advantages that plumb masts lack, otherwise they would not keep reappearing. One thing can be said; it is easier to cut sails for vessels with masts raked. <I did not notice that with Tyvek, but perhaps cloth panel sails benefit?>Their <raked masts> chief disadvantage is <when> running off in light winds, as the booms have a tendency to fall inboard and gybe. <Makes sense to me, though has not been of importance in light wind voyages with Aldebaran; possibly this is because the main boom is nearly horizontal, the end does not ride much higher than the jaws.>"
Sep 14, 2009, 11:23 AM
Registered User
capt_redde's Avatar
"Might not be a footy according toall rules tho!"

Aarrrr if we be pirates, then thee rules be more guide lines!

Beside I don't compete, I just sail me little ships!
Sep 14, 2009, 02:43 PM
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Brooks's Avatar
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Maiden voyage with the new course and lower topsail


A good maiden voyage of the Pyrate Brig. Winds were 3g6 mph and fairly steady. The ship looked good (if you were a pirate). She would tack and wear. Tacks were with a sternboard; the novice skipper (me) may be able to clean them up with more practice. Wears were a snoozer, very easy, as one might expect from a square-rigger.

Beating was easier than with Pamir (in the sense of making good to windward), but harder than with the topsail schooner rig. The course made good was less than the 4pts of the schooner and probably more than the 2-2 1/2 points of the Pamir. Even though my yards swing quite a bit, they still don't position the squaresails for a beat as well as the schooner's booms and gaffs position their f&a sails for a beat. Runs and broad reaches were easier than with the schooner, again reflecting the change in sail from f&a to square rig.

She sailed with royals struck as there was sufficient wind to dispense with them. Lee rail slightly under in the gusts, took on water, though not enough to affect trim. I did not even realize she'd shipped any seas until I pulled the cork and upended the hull at the end of the voyage. I should carry my hypodermic bailing pump (large size one from the vet supply section of the feed store). The cork drain plug is new, a "cologne bottle" sized one from the hardware, fitting into a hole in the forepeak deck. This allowed me to run more tape around the forepeak waterway, as I no longer had to depend on the non-waterproof seal there to empty water out. I'm not really sure why I took on water, will have to investigate. I did forget to install the copper pipe drains in the freeing ports (they are closed by the tape), so any deck load had no escape except to seep below decks. Part of the deck seams awthartships, and both mast step holes are unsealed, so tacks and wears that sent deckload surging across to the other side would send water over these openings, perhaps.

I moved the keel forward about 1" or so from the schooner and brigantine position. This was to account for the greater sail area on the foremast, compared to the topsail schooner, and the replacement of the schooner's big mainsail with the brig's small spanker. Both changes would shift the CE forward, and I moved the CLR (fin) accordingly. She sailed down by the head a little, I'll have to shift the Pb weight container aft to compensate.

The spanker did not have as dramatic an effect on helm as the schooner' large mainsail, which was to be expected. With the schooner, weather and lee helm is under control of the mainsail sheet: sheet in to induce more weather helm, sheet out for lee helm. The spanker's effect was more subtle; there was probably an effect, but the new skipper was mostly oblivious to any.

No movies, my cameraman is off for a week, working. His darn boss won't pay him to come play boats with me, if you can believe it..... The pirate brig needs victims...er playmates, so John, hurry home and get to carving on your hull :-)
Sep 14, 2009, 02:56 PM
**NOT GUILTY**
Capt.Crash's Avatar
Another nice job Brooks.
Sep 14, 2009, 03:21 PM
Damp and Dizzy member
Brooks's Avatar
Thread OP
Thanks, Capt. C. I enjoy your reports of your MMBC.

I forgot to mention that I did not have to move the masts from their schooner position. This was a pretty easy rig conversion.
Sep 14, 2009, 05:19 PM
Registered User
A short movie of brig sailing on various points here:
https://www.rcgroups.com/forums/show...0#post13113530
Sep 14, 2009, 05:30 PM
Diver-driver
meatbomber's Avatar
looks great and sails great !


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