Lively to gradual trim techniques

[HAL]

Let’s say you have two types of boats, both fractional sloops.
A is, wide, light, not a full keel, high aspect ratio sail plan, with a lively response to changes
B is, narrow, heavy, full keel, low aspect ratio sail plan, with a gradual response to changes.

What sail trim techniques can you use to bring boat A closer to B in response?

 

[Alan]

None

These a two designs are very different boats. Trim is trim, it's either right or its' wrong regardless of the boat you are on. Vessel A is a fast efficient sled while B is a much slower and lower pointing boat.

Trim can and should be adjusted for best performance, but nothing you do will change B into A.

 

[shemandr]

I would first be tempted to say reef the main to reduce aspect ratio, rig a drouge to increase drag, hoist some weight in the rig to raise the center of effort ... but,
If you wanted to trim a performing boat to sail more like a CCA design there are a few things to be done. You could decrease backstay tension to sag the forestay which would make the jib more powerful but less pointy. Put some crew on the rail to keep the boat on its feet. Increasing halyard tension for the jib would bring the draft forward and make the sail more forgiving with a wider groove but more difficult or impossible to drive as high. Adjust the jib cart back (Decrease power and lower center of effort) and out on the rail (Make less pointy but faster on close reach). For the main traveler up and sheet eased to open the top of the sail reducing power, heel and lowering the center of effort for the main.
Overall the trim adjustments I've suggested make the sails less like high aspect ratio sails, reduce the ability to go to weather and make them more forgiving of driver inexperience, errors or poor conditions to point. But as I'm writing this I wonder if increasing the power of the rig accomplishes the stated goal - making A more like B. Nevertheless, that's my answer so let the flames roar and lets see what others say.

 

[sailingdog]

I would first be tempted to say reef the main to reduce aspect ratio, rig a drouge to increase drag, hoist some weight in the rig to raise the center of effort ... but,

Just curious, but how does hoisting a weight in the rig raise the center of effort??? it raises the center of gravity, but a compact weight wouldn't raise the center of effort significantly in any way I can see.

 

[Barnacle Bill]

Shemandr has a good sense of humor. Don't know why anyone would want to make A sail like B. Much more fun to sail the A boat in any condition. As far as weight aloft, it has been proven that a boat with a carbon fiber mast (less weight aloft) can carry sail longer in increasing wind velocities, while the heavier aluminum spar'd boat must reef a little more quickly in the same conditions. Also carbon decreases pitch polling in heavier sea conditions, or when cutting through big powerboat waves, etc.
It seems most people who own B type boats rationalize the poor sailing quality with other justifications like her interior comfort, etc. or they say, my boat sure reaches well. Any boat will sail off the wind well when the wind is blowing hard enough, but can it go to weather? A common saying used to be, "gentlemen don't go to weather". When that statement was introduced, boats couldn't sail to weather (poor designs for windward performance in cruising boats). The old Morgan Out Island series suffered from good windward performance to the point that you had to turn on the engine to tack. I know some Island Packet owners who say the same thing. But, both companies sell lots of boats. The Morgan Out Island was the most popular boat for charter use in Florida and the Bahamas back in the early 70s and today you see lots of Packets sailing around the Bahamas (shallow draft helps). It is what it is. You just try to make what you have sail the best it can (if you want). The best thing is to enjoy what you have and if you don't enjoy how it sails, get something else.
I once got on an O'Day 32 that was for sale. The owners/sellers were on board as were the buyers. I was along for the ride. I started to help rig the boat and hoist the sails and get it underway. I looked at the lead for the genoa and saw that it was not in the right spot as we sailed to weather. I changed the lead to the proper location to make the boat sail better and the owners started yelling at me for changing the lead. Perhaps I should have asked first, but they said, "this is where we always have the lead". My point is they had it in the wrong location every time they went sailing and didn't know it. I was just trying to make the boat sail better, but backed off and sat down. So, that is was what they wanted and liked and it was their boat only for a short time there after as it was soon sold to the other folks who better enjoyed their new boat with the lead in the right place (or so I guess they did).

 

[h2ot]

WHY

It sound like the captain purchased a boat that the first mate doesn't like to sail on!
Why would you want spoil all the best attributes of a high performance boat and make it sail like a heavy cruiser? The simple fix would be to reduce sail area by 50%.

 

[Don Guillette]

Re: None

Alan, as always, is spot on and he gave my thoughts in 3 sentences. There is no comparison beteween these 2 boats other than they are sail boats. As Alan suggested - sail both to 100% and you get what you get out of each of them.

 

[HAL]

Thanks

Thanks for the ideas. Sometimes it’s fun to be lively and tweak things for maximum performance and other times it’s fun to be gradual and get to things when you get around to it.

 

[RichH]

Not so ...
Heavy full keeled boat differ greatly from lightweight fin keelers.

Agree that perfect trim is important but to attain that with a 'heavy' requires a lot more.

A heavyweight full keeler will not accelerate as well as a fin keeler, a full keeler will be hard to turn into and out of a tack

'At speed' sailing requires flatter sails (watch your telltales)... Powering out of a tack after a fullkeeler has lost most of its momentum requires a 'LOW GEAR' shape/trim setting. In between being almost stopped and full speed requires gradually retriming while you watch the VMG and the speedo. You can easily 'get away' without powering up and down in dinghies, lightweight sportboats and finkeelers .... but you really have to 'shift the gears' to sail a narrow heavy full-keeler well.

Powering-up during a tack on a full keeler needs: opening the distance between the jibs leech and the main, dropping the main traveller a bit, hooking the battens to weather a wee bit, .... if possible - easing the main outhaul (if convenient) to get more draft into the main.

A full keel heavyweight does NOT like to tack. Tacking is for fin keelers, straight line sailing is for full keelers. If you force the wheel/tiller, the long keeled boat will almost come to a complete stop. Rather as you enter the tack, pull the mainsheet in with a lot of force .... to hook the aft ends of the battens 'up to weather' (like putting down the flaps on an airplane) this will increase heel which will increase weather helm .... and you tend to 'sail the boat through' the tack instead of entirely depending on the rudder. With a full keeler dont ever get into a tacking duel with a fin keeler. Use your momentum to 'bash' the waves out to the way when its boisterous - an advantage that fin keeler usually wont have.

First Gear for accelerating: Full draft, battens slightly hooked to weather, traveller slight dropped and jib leech allowed to fall a few inches further off the spreader tip. Tell tales flying perfectly (at this slow boat speed). Attempt to get as much increased draft into the TOP of the mainsail as possible .... but dont put in too much power or the fullkeeler will heel over too far and begin to 'skid off to leeward' - watch the rudder wake: it should remain straight with the boats centerline, not coming off at an angle

High Gear ... Second batten from the top --- ***aft end of the batten perfectly aligned with the boats centerline*** .... then do all shape and trim to keep the mainsail's tell tales perfectly flying and that second from the top batten 'parallel' so there's lots of 'umph' in the top of the mainsail.

Between low gear and high gear .... watch the tell tales, VMG and speedo then make slow trim/shape adjustments until at FULL speed. Do shape/trim corrections gradually (always TWO corrections, never 'just one').

Dont make any sail adjustment without consulting the speedo and VMG ... these two alone are the ultimate judge and jury.

 

[shemandr]

Sailingdog is correct - I should have said center of gravity not center of effort. I'm not a physicist but I .......

 

[HAL]

A&B

Thanks again.I understand A & B better now.

 

[Ray Bowles]

Send them both to the Bahamas from Miami in a 25 knot wind out of the northeast. I'm sure that no matter what boat A does he will arrive about the same time. I'd advise that they only drink sundowner brews that were carried on boat B. I remember being boat B.
Ray