USS Constitution Project

I've started working on a 1:48 laser cut USS Constitution kit to help the AOS format. I've followed the AOS threads and considered doing a sailing kit, but I know almost nothing about sailing. In fact, above the deck I can identify what is a mast and what is a sail (just don't ask what type of mast or sail) and almost nothing else. So this thread will document design of the kit and I'll pose questions from time to time on rules interpretations and sailing terminology.
I've already partnered up with Kotori87 and he has provided a set of plans to work from, as well as some much needed advice. I was able to get the basic ribs and keel done yesterday:

The hydrostatic calculations show a displacement of 1226 cubic inches at the design waterline. That's 44 pounds displacement! And it will increase slightly, because that volume doesn't include the volume of the keel.
The Constitution dimensions are such that the top of the penetrable area, 3" above the waterline, falls directly on the deck or a little below it. So in the picture below the top red line is the bottom of the sub-deck, while the top green line is 3" above the waterline. I was surprised at how high the 60 degree turn of the bilge is. The middle red line represents the top of the bottom hard area and it never reaches the second green line, which is 2.5" below the waterline. Just for comparison, I plotted the 45 degree turn of the bilge. It is the lowest red line and it just barely gets below the -2.5" line.

 

OK, first question. Since the rudder can be 300% oversized, what is the best way to get the extra area? Below is a drawing of the original rudder, which has about 7 square inches below the waterline, as well as a 200% and 300% version. I kept all of the area above the bottom of the keel, to protect the rudder when it is on the bench. Should I extend the rudder below the keel to make it taller and narrower, or is the current drawing OK?

 

My initial plan was for removable decks and masts that can be un-stepped for transportation. I've seen pictures of ship with the removable top section and it looks pretty nifty. I'll need more information on where the lines and servos need to go before I'll know if it would work for us. Additionally, I'm not sure that that there is 1"-2" that could be lifted off, since the hull needs to be penetrable up to the deck. I'll look into whether the masts can be attached to the deck and the servos to underside of the deck. That way the lines would not need to be disconnected when breaking it down for transportation. I think there are plenty of good ideas like this, and the more that we incorporate into the kit the easier it will be for the beginning sailor to get the ship on the water.

 

Wow, thats awesome, I am wondering if you could make the same kit, but raze it a level, then you could have a corvette hull from basically the same kit, I had tried to find a hull in which I could make a three decker, and each successive hull from the same plans produce it a deck lower, to have three different ships from the same hull. A third rate, a Frigate, and a Corvette, but with so many projects already. The only thing i was able to do is read up on Sailing Men of War.

 

Ahoy, folks!

So... the "official rules" document says that the hull shall be penetrable "down to 60 degrees down the turn of the bilge", or 2.5 inches, whichever comes first. Problem is there are two different ways to orient a 30-60-90 degree triangle, and I don't remember which way I originally intended it to be oriented. So which way would you guys prefer? Or would it be better to go with 45 degrees, since that's the one everyone is familiar with already and it works whichever way you position the triangle?

Another thing to think about: the extended keel. From my experience, and research on other models about this size, it will be a rectangle of about 8" to 12" long by 8" to 12" deep, and will need to hold 15 to 20 lbs of ballast on the end, even if the ship is heeled 90 degrees over (strong gust/knockdown conditions). Both the keel itself and its attachment to the hull need to be strong enough for such a load. What material should it be made of? And how should it be attached? I have a few ideas but right now it's bedtime for me, so I'll write them up later.

 

Mr. Brooks, who has much expirience building and sailing these ships and occasionally posts here, once mentioned that the extra rudder area is better straight back instead of downward past the keel. He also suggested 300% is a good palce to start.

For keel ballast, the one used on the Requin is probably not a good way to go. Kotori's flat plate style with weight at the end sounds like a good method to go with. Attachment could possibly be bolting it to the keel itself, or to a metal "doubler" alongside the keel itself?

I like the idea of a 45 degree angle. Most clubs seem to use that standard and it is familier.

 

I like the 45 degree idea, too. No idea what I was thinking when I originally chose 60 degrees. lets wait until Friday, to see if anyone objects, then update the rules to say 45 degrees instead of 60.

About the keel: the plate keel is more suitable for square-riggers, but what material should it be made of? 1/4" plywood would be best, since it can then be cut at the same time as the other parts. But is 1/4" plywood strong enough to hold up under the load of a heeled-over ship? I don't know, and unfortunately I have no good way to test. Would someone who has access to 1/4" plywood and a lot of weights be willing to run an experiment?

 

What all would I need to do the test? I have 1/4" plywood and lots of lead. I am lacking a boat though. ( hmmm, that might be a problem)
Beaver

 

Here is a link to a gorgerous big 200 gun Ship of the Line called the Santisima Trinidad. The builder did an amazing job! The part of the build thread I want to point out starts on page 16 for the ship's first test sail when the ship layed on it's side to page 17 where the builder and expirienced square rigger sailors discuss the keel weight. The last page gives a couple good ideas of how to attach the weight solidly against the bending forces of the heeling boat.
www.rcgroups.com/forums/showthread.php

 

If left at 60 degrees, the Constitution has 172 square inches of penetrable area per side. Lowering the standard to 45 degrees increases the area to 202 square inches, or about 17% more. I'm willing to change the notches if you decide to adopt the 45 degrees.
The weighted keel can also be made from two layers of 1/4" wood. I assume you want it removable? An 8" x 12" plate keel is going to seriously limit your turning.
Of course I thought real men would want to sail the ship the way it was designed - no new fangled mechanisms under the keel that would prevent you from chasing pirates up shallow coves.

 

Flat plate keel:
1/4" plywood is plenty strong enough. I actually use a thinner birch ply for my 24" hull topsail schooner/brigantine/brig (several rigs tried for fun, all work). The birch has 5 layers, rather than the 3 layers in common plywood, so it was possible to make a nice airfoil shape w/o wood chipping out.
My Pamir's first 2 keels were made from regular 1/4" plywood - it chipped out, but did not seem to affect speed that much, so you don't need to buy expensive birch plywood. The current keel is 1/2" birch ply with an airfoil...looks nice and works well, but is a refinement to be sure. I'd recommend starting with cheap 1/4" ply, and once you've decided on the best sailing shape and area, then refine it if you wish.
Start with a Large keel, lots of area. This ensures your boat has the capability to work to windward (after you learn to sail her, of course...don't expect instant success, at least I didn't achieve that Then, as you learn your boat, you can try reducing keel area to increase speed and turning rate. Forget entirely the long, narrrow keels common to racing sloops. A square rigger simply does not move fast enough, on a beat, to generate enough lift off the sloop-style keel. You need a low "wing-loading" for squarerigger keels if you want to sail to windward.

My keel bolts to an aluminum L shape that is, itself, screwed to the bottom of the hull. This makes removal of the keel convenient for transport to and from the pond. Both my 36" Pamir and 24" Aldebaran have suffered knockdowns w/o the keels coming off (either from bending the aluminum L or breaking the plywood). If you hold my boats laid over 90 deg out of water, there is some flexing of the L shape. I don't know if it flexes when the boat is in the water, but I'd doubt it - thewooden keel (and the lead weight itself) has bouyancy in water that reduces the torque, something that is not present when the boat is in air (well, yes there is bouyancy in air, but it's so small as to be negligable).The only time spent laid over in air is when I'm attaching the keel or detaching it. The hull lays on a picnic table, with spars out over space, while I add or remove bolts. When I pick up the laid-over boat and keel, I pick up by the keel, putting my hands right next to the hull. I support the keel with the other hand...so I don't deliberately stress the L, but I don't take super special precautions either.
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The length of keel will affect your turning rate...but I don't consider that significant for my squaresail maneuvers. Squareriggers will not spin on a dime like a sloop. You have to sail them around a wear or tack, you can't just jam the rudder over like with a sloop. So, the rapid turns you see in the racing sloop fleet are not available to a squarerigger... which means that a long keel is not so disadvantageous. The main thing is to have enough keel area so that you can work upwind. W/o enough area, your boat will sag off on a beat, and you won't make ground to windward...been there done that

 

Real ships did not need big finkeels because the hull itself makes an airfoil. It's the lift of the underwater airfoil (the hull) that lets a boat sail to windward. The lift counteracts the drag of the wind, which is always pushing the boat to leeward. Model hulls make airfoils too, but they generate insufficient lift to counteract the wind drag. Thus, we add wing area (the fin keel).

If you watch closely, you can see the lift of the hull+ keel when you launch. When you first release the boat on a beat, it will sag to leeward. Then, as the hull picks up speed, you will see the boat curve up to windward and start making good. Wind and wave conditions have to be favorable to see this, but it's happening all the time. Boats and sails are lift devices, just like wings on a plane. Once you make the connection, all your rc plane, or balsa wood hand glider, knowlege will serve you well

 

Good to see you Brooks! And glad to have your input on this project.

 

How do square riggers work with very short to no fin keel sail? Seen a few pictures of boats with a long weight attached directly to the bottom of the hull.

 

Hi Brooks, thanks for your input! My experience with mini-Constitution was similar. I first tried a few bathtub tests without an extended keel, and found that wind and water do not scale. The ship was so unstable as to be incapable, at its small size, of staying upright. Unlike the historical ships, we need some kind of extension to lower the COG, simply because wind force, righting forces of stability, and weight distribution do not scale. The other forces and effects that make a sailing ship work also do not scale, which is why the keel needs to be large, as well as deep. The use of enlarged keels is not a problem in and of itself, because different shapes offer different tactical trade-offs.

When I first launched mini-Constitution, she had a 12" long by 8" deep keel. She made very little leeway (down-wind drift), and could point upwind very well. However, her top speed was limited by the drag from the extra surface area, and her maneuverability was noticeably hampered. After a while, I tried out a smaller 6" long by 8" deep keel, and found her performance changed. She had noticeably more leeway in light winds, but was also slightly faster and turned much better. With every keel I tried, I had to be careful of large clumps of weeds, and of course shallow water. If I did accidentally run into those, however, I had simply to back all sails to reverse away from the obstacle. I never tried a shallower keel, but I expect that will have different effects on performance, too.

 

RichelieuBB - I've not seen the Steele Hutchinson Chapman squarerig kits sail in person. Those are the boats (brig and frigate over on rcgroups.com Scale Sail forum) you are referring to, I am guessing. They are beautiful scale models, museum-class with a talented builder. My impression is that the owners are more into building than sailing efficiency, which is fine, just not my cup of tea. The larger the model, the more effective the hull as a waterfoil, so perhaps they can get by with their smaller fin keel. But I am confident they would sail better with a deeper, bigger finkeel simply because small, full- sized sailboats (eg. Sailfish, Sunfish, Lazar) need a finkeel (daggerboard) to go upwind. One of the builders told me that he does not make good progress upwind (he usually has to tow his boat back to the launching area). His lack of success is undoubtedly influenced by his lack of sailing practice, though (model builder not model sailor), so it's hard to know how much is due to technique and how much is due to lack of sufficient keel area.

When you sail your model for the first time, it's wise to sail on a pond where you have access to the entire shore. If your model is not debuggged, or your squarerigger sailing skills are not polished, you will likely be retrieving your model from the lee shore (or far shore if you can't tack or wear) at some point in the day...been there done that A Lot, hoho. Launching in a small cove at the leeward side of the pond will save you some walking time; the boat will either end up on the leeshore, or on the other side of the cove if things don't go as you wish. A 100' wide cove is plenty of room to see if you have got her balanced right, both for roll and for maneuverablility.
One big advantage of bolting your finkeel to the L is that you can predrill the L with several bolt holes while at home. Thus you can move the finkeel fore or aft to improve tacking or wearing. I've had boats where I so misjudged the finkeel location that they'd neither tack nor wear. If I was maidening on a big lake, I'd be out of luck unless I had a row boat *Immediately* available to chase down the model. Prepare the rescue boat before you launch, or be sure you can get to the other side of the pond in a reasonable amount of time.
If you can't find a small pond, then nothing wrong with tying a strong line to the bow of your model. I've used a fishing pole and floating flyline (plus backing), using only the base segment of the pole with the reel. If you lead the line to the windward side of the hull before you launch, you can always pull the bow around to tack and have her sail back to your feet.

 

First, a slight correction on the penetrable area: The 45 degree line results in 198 sqin per side, not the 202 sqin I stated earlier. So moving to the 45 degree line adds 15% to the penetrable area. The -2.5" line is on the waterline when the ship is at an approximate heel angle of 25 degrees.
For the keel: I can extend the main keel a couple of inches to give some area to bolt the lower keel on. If I make a sub-keel with two doublers, it can easily be attached with bolts. This would give a total thickness of 3/4", plenty of material to sand to an airfoil shape. In the below drawing, the keel extension is 9" long and 11" deep. There are extra holes in the main keel to permit moving forward or back up to 2". Once a satisfactory location is found, the extra material on the main keel can be trimmed off.