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Bryan Beamer
Master Marine Consultant

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USA
1038 Posts

Response Posted - 03/26/2003 : 14:11:30

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>I’ve never been sold on the idea of adding 300 lbs to the bow of a boat in order to pitch the bow-down and reduce weather helm, <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I am only talking about my experience with my c250wk. Adding weight to the bow in my case was to do more than reduce weather helm.

IMO adding the weight actually make the water line longer. Picture this. Looking at a c250 there should be an equal amount of space between the water line stripe and the water all around the boats waterline. Looking at a c250wk without any added weight in the bow and no people on the boat there is 6" of space between the line and the water at the very front of the bow. Now look at the stern the line has water right at the bottom of it. Now put 3 crewmembers in the cockpit (me 240lbs, 1 crew member 155lbs and 1 @ 195lbs) the waterline is now half covered and the bow is now 8" between the line and the water. This is not making the waterline longer it is making the water line wider behind the keel and shorter in front of the keel. Since the boat bottom is wider from the keel back than it is from the keel forward this increases the wetted surface witch slows you down. The water line is the waterline you can't extend it past the stern on a c250. You can only bury it deeper into the water. The deeper the stern the higher the bow is out of the water.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote> When you pitch the boat bow-down, the stern is raised<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Now add weight to the bow with no one on the boat until the boat sits with the same amount of space around the line and the water. Put the same crewmembers on the boat and look again. I my case there is less than a 1" change (with the weight in the bow). This has now put the bow down into the water where it is suppose to be and has narrow the wetted surface behind the keel. So with the weight the boats waterline is longer and the wetted surface is smaller behind the keel.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>It takes wind power to push that 300 lbs around all the time. In the absence of that 300 lbs, that wind power would be used to make your boat go faster. <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Again IMHO wouldn't you rather have 2 extra 150lb people laying in the bow than having your stern buried in the water? I think it takes more wind power to fight a buried stern then it does to fight an extra 300lbs in the bow.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>The C-22 only has one pair of lower shrouds and one pair of uppers. <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

If I’m not mistaken the older c22 had 2pair of lower. They did not change it to 1 pair until the mid to late 80's

Bryan Beamer
<img src="http://im1.shutterfly.com/procserv/47b3dc23b3127cce9462f2858f2b0000001010" border=0>
Daylight Again
C250wk #495

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2984 Posts

Response Posted - 03/26/2003 : 20:35:03

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
Some C-250 racer is going to experiment with different ways of configuring his boat, and find the configuration that is the most efficient on all tacks. Whoever analyzes it correctly and gets the best overall performance out of his boat is likely to run away from the others at the nationals.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Steve, very well put thoughts.

I agree with the above statement... And I also agree that adding weight to balance the boat is not a great way of solving the problem. But part of the problem may be the Nationals rules are set up for one design and therefore modification restrictions apply that might not under PHRF racing.

The C250 has a single set of lowers...and btw...a C22 has two sets of lowers just like the C25 and can enjoy a backstay tensioner.

In order to do away with the forward lowers, radical raked spreaders are used to hold the center of the mast forward. This eliminates running a loose rig and using a backstay tensioner as to draw the mast head aft any would loosen the uppers and release pressure on the spreaders which hold the mast both forward in the middle and in column.

There is a way however to run a backstay tensioner and thus a loose rig... but I'm not sure how design legal it would be. It is to run a baby stay. Unfortunately, the foredeck doesn't offer much support for a traditional baby stay so it has to be taken all the way to the stem. As can be imagined however, it would get in the way of a tack. This can be overcome by making it a running baby stay (running rigging rather than standing rigging). Here's how. A low stretch line is run from the spreaders to near a turning block at the mast base. A bungee is run from the spreaders down thru the block and made to the end of the line. The bungee retracts the line to the mast. Made to the end of the first line, another low stretch line is run thru a block at the stem and back to a sheet winch.

When needing to use the backstay tensioner, the baby stay is hauled tight which pulls the middle of the mast forward against the counter force of the lowers. This allows the masthead to be hauled aft without serious consequences. Both the main and jib are flattened with only a slight bit of masthead movement to leeward but not serious. A rotating mast would be nice in that it would transfer that slight leeward movement into beneficial prebend.

So, a tack would require additional effort...the running baby stay would be released... and then reset.

Probably better than sandbags forward would be to move the mast forward, again I think outlawed in our Nationals rules. I think Capri 26's have seen this help. I think we may be allowed one inch of height addition. This would be a far better way of stretching the "lead" distance because in doing the sand bags... as you say, there is additional weight which is counterproductive and there is some loss of aft latteral resistance.

I think it would be really cool for a winger to move the mast forward 1-2 inches and see what happens. We do this in a fashion very easily on the water ballast models... we simply rake the center board aft which yields big gains in latteral resistance aft. On a wing...they would be gaining "lead" length without compromising weathering ability by adding bow weight.

Another thing that I've advocated and in fact talked to Catalina about is the need for additional latteral resistance aft which could be had by adding a skeg. Gerry Douglas didn't think it would be of help. However, Catalina did follow our lead and added a center board stop which holds some aft rake to the board. I think that translates into acceptance that more aft latteral resistance was needed.

Moving the mast forward some would effect the same result. The larger high lift 2nd and 3rd generation rudders with much greater drag effectively increased latteral resistance aft as well.

One legal tactic in light air would be to run the 1st generation rudder on the water ballast with its center board raked aft a good amount. It handles light air just fine and has far less drag than the much larger and draggy high lift foils of the 2nd and third. On top of that...the 1st generation is a balanced rudder. While I understood the need for more lift from the rudder and hence why a 2nd generation...I never grasped why they went from a balanced design to a non balanced... and of course ultimately a 3rd generation which was balanced. I have suspicions that the 2nd generation was a product of existing molds.

Wow..Ive rambled...enough

Arlyn C-250 W/B #224
<img src="http://www.stewartfam.net/arlyn/rr.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.cox-internet.com/arlynstewart/"]Arlyn's C250 Mods n Cruisin Stories[/url]

Edited by - arlyn stewart on 03/26/2003 23:40:56

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Bryan Beamer
Master Marine Consultant

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USA
1038 Posts

Response Posted - 03/27/2003 : 02:44:05

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote> If I’m not mistaken the older c22 had 2pair of lower. They did not change it to 1 pair until the mid to late 80's
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I was mistaken. The c22 always had 2 pair of lowers even in the mid to late 80's. I was thinking of another sailboat make.

A picture of a 1986 c22

<img src="http://wl.iglou.com/strsail/c2286b.jpg" border=0>

A picture of a 2003 c22 Mark II

<img src="http://www.catalinayachts.com/gallery/bay_C22II/C2202.jpg" border=0>

By the way has anyone seen the new Catalina 387? The lay out looks pretty nice on Catalina's web site

http://www.catalinayachts.com/main.phtml

Bryan Beamer
<img src="http://im1.shutterfly.com/procserv/47b3dc23b3127cce9462f2858f2b0000001010" border=0>
Daylight Again
C250wk #495

Edited by - on

John Mason
Admiral

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USA
687 Posts

Response Posted - 03/27/2003 : 13:05:33

What would happen on a spinnaker run with that 300 lbs. in the bow? Wouldn't all the crew have to sit on the transom to keep the bow from porpoising?

John Mason
<img src="http://www.users.qwest.net/~jamason/ali.jpg" border=0>
pronounced "Ali Paroosa"
1982 - FK/SR #3290

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Steve Milby
Past Commodore

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USA
5932 Posts

Response Posted - 03/27/2003 : 19:40:03

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Wow..Ive rambled...enough <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Not at all, Arlyn. This stuff is interesting.<img src=icon_smile_approve.gif border=0 align=middle>

Steve Milby "Captiva Wind" C-25 T/FK #2554

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 03/27/2003 : 22:04:38

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
When you put tension on the backstay adjuster, the masthead does move aft a little bit, but the lower part of the mast bows forward, pulling a lot of sailcloth forward with it. The overall effect is to move the CE forward, which reduces weather helm.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
Hmmm... Isn't this fun? But as I understand it, when you pull the mast back against snug forward lower shrounds, the reason the CE moves forward is that (1) the mast bend flattens and depowers the main, while (2) the jib/genoa gains some power from the straighter forestay. While pulled against the forward lowers and held at the bottom by the mast step, I don't see how the mast bows appreciably forward.

Why does the bend flatten the sail? Normally, the main has a pocket that is formed by the leech being relatively tight compared to the area in the center of the sail. (The older the sail, the deeper the pocket.) As the mast bends back, it takes the tension off the leech so that the downward force of the boom (from the sheet and the vang) is more evenly distributed across the sail, flattening the pocket. As the sail gets flatter, it deflects the wind more efficiently instead of catching it in the "pocket." The CE of the sail moves forward closer to its geometric center, and the CE of the overall rig (including the headsail) moves forward.

But maybe I'm wrong...

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette-Honda "Passage" in SW CT

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Arlyn Stewart
Master Marine Consultant

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USA
2984 Posts

Response Posted - 03/28/2003 : 10:53:42

Dave, the backstay tensioner has the effect of hauling the mast truck aft and bearing down on the mast. The process affects the mainsal by bending the mast. As you say, the point at which the lowers and spreaders is fixed... so the term bending the mast foward is a relative term...in truth, the mast is being bend my moving the mast truck aft so that the apex of the mast bend will be evident at the spreaders and lower stays.

The effect on the mainsal is to widen the distance between the luff and leach in the area where the mast is bowed forward and in that process, the pocket is reduced.

This process is also done on sails with adjustable battens. They also allow setting the curve of the sail by sanding the fiberglass battens thinner at the point the foil apex is wanted... but back to our boats.

I don't think the leach relaxes any due to the mast head coming aft... as the mainsheet will still firm it up... and in the process as I think you were saying... flattening the shelf on the lower main. So, there are likely at least two dynamics occurring on the main. The middle is flattened by the mast bow and the bottom is flattened by the lowering of the boom. BTW... yall have a downhaul on your boom that the c250 doesn't have. We are limited to the halyard for luff tension.

Tightening the forestay...depowers rather than powering the jib by flattening it and reducing its lift and drag. Depowering to gain speed is opposite of most racing dynamics but none-the-less the case with sailing. Flatter allowing air to flow faster over the jib and mainsail and faster moving air has the effect of moving the center of the foils lift forward.

On a 90 mile crossing of Lake Huron... we were fortunate to have ideal conditions with winds 15-20 on or slightly ahead of the beam with chop not exceeding 2 feet. These conditions gave me my fastest sustained boat speed with the c250. With the backstay tensioner hardened, two turns of reef on the 110 jib and full main... we busted along at one point for over two hours at 7.3 knots with the helm locked and no attention given to the boat. The CE had moved so far forward at that speed that there was no attempt by the boat to round up... She was balanced so well that the little bit of hunt she was doing to stay in balance was mostly imperceivable.

A couple of observations from that experience. 1. The two turns of headsail furl on the 110 likley helped move the CE forward. 2. To get it going like that...the jib can't be twisted off. So, while we had slightly too much wind for all sail...rather than twist the jib off it was reduced by two turns. 3. we were heeled a fair amount...likely 15-20 degrees...which is basically contrary to most go fast thought.

When winds continued to build... forcing a single reef in the main... we lost the go fast speeds though we did continue at hull speed of 6.2 kts.

It may be that to plane which seems to me what we had to be doing...she needs to be laying over some... I don't know.

BTW... the video that I offered a while back is from that segment of sailing.... I will offer it again.

http://www.stewartfam.net/arlyn/c250_3.WMV

Arlyn C-250 W/B #224
<img src="http://www.stewartfam.net/arlyn/rr.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.cox-internet.com/arlynstewart/"]Arlyn's C250 Mods n Cruisin Stories[/url]

Edited by - arlyn stewart on 03/28/2003 10:55:09

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Steve Milby
Past Commodore

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USA
5932 Posts

Response Posted - 03/28/2003 : 12:45:53

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote> While pulled against the forward lowers and held at the bottom by the mast step, I don't see how the mast bows appreciably forward. <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

That’s a good question, and I haven’t found anything in Ross’ book (Sail Power) that explains it. My best guess is that when you apply tension to the backstay adjuster, it pulls the top of the mast aft. Initially, the mast can’t bend aft, because the forward lowers are holding it. The only way it can bow is forward. The aft lowers become taut, to prevent the mast from breaking. As the aft lowers become taut, the forward lowers are relaxing. The forward lowers resist the initial pull of the backstay adjuster, and they cause the mast to start to bend. But, after the mast has begun to bend, additional pressure on the backstay adjuster pulls downward, and that downward pressure is what causes the mast to bend even further. As it bends further, the bow in the mast thrusts even farther forward. I suspect that if you checked the tension of the forward lowers when the mast is at maximum bend, the tension on the forward lowers would probably be less than when the mast is only slightly bent, because of the way the bow in the mast is thrust forward as it bends.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Why does the bend flatten the sail? <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Imagine that you are holding a two-foot long piece of string between the thumb and index finger of each hand. Hold your hands 1 ½ feet apart. The string will have a catenary curve in it. As you move your hands farther apart, the string will straighten out. That is how mast bend flattens the mainsail. As the mast bends, it pulls the middle of the sail forward. Tension on the mainsheet and the boom vang keep tension on the leech of the sail, so that the leech can’t move. When you bend the mast, you are doing the same thing as when you moved your hands farther apart. Bending the mast lengthens the distance from the leech to the luff, and that takes the curve out of the mainsail, flattening it.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>…as I understand it, when you pull the mast back against snug forward lower shrounds, the reason the CE moves forward is that (1) the mast bend flattens and depowers the main, while (2) the jib/genoa gains some power from the straighter forestay. <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Bending the mast depowers both the mainsail and the jib. Straightening the forestay flattens the jib, depowering it. You use the backstay adjuster when the boat is overpowered while beating to windward. It flattens both sails, which reduces heeling and excessive weather helm.

Steve Milby "Captiva Wind" C-25 T/FK #2554

Edited by - on

Bryan Beamer
Master Marine Consultant

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USA
1038 Posts

Response Posted - 03/29/2003 : 02:37:22

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote> BTW... yall have a downhaul on your boom that the c250 doesn't have. We are limited to the halyard for luff tension.
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

or a 3 to 1 Cunningham

Bryan Beamer
<img src="http://im1.shutterfly.com/procserv/47b3dc23b3127cce9462f2858f2b0000001010" border=0>
Daylight Again
C250wk #495

Edited by - on

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