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racing trim ?

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JimB517
Past Commodore

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USA
3285 Posts

Initially Posted - 04/01/2008 : 12:06:16

Is it better to pump the portside 15 gallon water tank dry and lighten the boat but have a port list?

Or keep the tank full and have the boat nearly level?

78 fin, port engine/fuel tank, boat lists about 5 degrees even with tank full.

Indiscipline 1978 FK SR #398

Edited by - JimB517 on 04/02/2008 11:39:26

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 04/01/2008 : 12:57:26

Also, is it better to put extra weight in the bow to trim the bow down or have the stern squat? With my 250 lbs, my crew, my large 4 strok motor, and ample fuel, the stern certainly sits low.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/01/2008 : 12:59:46

Well, let's see... The water is about 124 lbs. that favors a starboard tack. Your list favors port. The boat will be lighter and favor port a little more; starboard a little less. So strap the beer cooler onto the starboard settee, and rock 'n roll.

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Dave Bristle
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Djibouti
10005 Posts

Response Posted - 04/01/2008 : 13:03:37

If your transom is in the water, it generates more wake and therefore more drag. Maybe the beer cooler should go on the starboard V-berth.

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Steve Milby
Past Commodore

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5895 Posts

Response Posted - 04/01/2008 : 17:05:48

In stronger winds, I'd fill the tank to help level the boat, and perhaps just enough ballast forward to level the waterline a bit. In addition, I'd stow anything heavy to starboard, such as the cooler, toolbox, etc., and I'd move crew weight around to keep it level while sailing to windward, except in light air, when you want to put crew weight to leeward, to induce a little heel to leeward.

My thinking is that in light air that extra weight will hurt more than it'll help, but in heavier air, the weight will help in and of itself, but it'll also help by leveling the boat and thereby reducing drag.

When sailing downwind, I like to move crew forward (just forward of the shrouds) and to leeward. That causes the boat to heel slightly, and it raises the stern up a bit. The bow is the narrowest part of the boat, and the stern is much broader. Raising the stern lifts the transom partly out of the water, significantly reducing the amount of wetted surface of the hull, and that reduces drag.

Edited by - Steve Milby on 04/02/2008 07:24:05

JimB517
Past Commodore

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Response Posted - 04/02/2008 : 11:38:52

I'm preparing for a 36 nautical mile round trip offshore race around the Coronado Islands. The race starts and ends in San Diego Bay, reaches out 18 miles. I will start and end in Mission Bay, adding about 30 additional miles.

Well last night I pumped the tank dry, took my 2nd anchor and chain home, my anchor stablizer, my auxilary fuel tank, some other stuff, and in total lightened the boat by about 200 lbs.

I redeployed some of my tools and spare parts to the starboard. My batteries have already been moved to starboard.

I took about 75 lbs out of the V Berth area.

The boat is sitting about the same on her lines and the port list is not any more noticable then before (about 5 degrees). We'll see how she behaves with this much weight off her.

I could remove 25 feet of 5/16 anchor chain from the anchor locker (leaving me with 25 feet of chain + 200 1/2 nylon rode) but I anchor a lot on short scope and I love the secure feeling I have with 50 feet of chain down and I need to be prepared to anchor in San Diego Bay either before or after the race if I decide to overnight and come home the next day.

I have a 7 gallon fuel tank in the port locker. A lot of boats remove their outboards when racing, storing them in the cabin. That is not practical for me because the Tohatsu is over 100 lbs. I need a lot of fuel because I have to motor about 3 hours just to start the race, and need to have fuel to motor back after. Plus the wind could die out there and I'll need to motor back. I figure I need 5 gallons.

One thing I could do is remove the fuel tank while racing and store it forward under the mast.

I got out my tiller extender and will have crew sitting forward, especially on the downwind leg.

I did some calcualations regarding spinnaker.

To fly the spinnaker costs me 19 seconds per mile. I am rated 247 without it and 228 with it. That is 11.4 minutes over this course. It should be downwind just aft of a beam reach to the islands and a beat back, perfect for the spin on the way out. According to my calculations, if the spin increases boat speed by just 0.25 knots for 1/2 the distance of the race (18 nm) I'll make up the 11 minutes. That seems like a clear reason to use it unless the winds are very strong and I am making over 6 knots without it. In my experience it adds about 0.5 to 1 knots off the wind in light to medium air.

Edited by - on

wmeinert@kconline.com
Past Commodore

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USA
353 Posts

Response Posted - 04/03/2008 : 08:02:06

As an avid racer I'm always looking for ways to get more boost, and I too kept the boat light, or so I though until I gutted it this fall to replace all the interior wood work with new. When I emptied what I though was a light boat, I found I literally had over 750 lbs of miscellaneous gear. Anchors, foul weather gear bag that weight over 50lbs and so on. It is amazing how much crap accumulates over a 5 year period since I last gutted the boat. Always put the weight forward downwind, and up wind on a tack and you win.

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Steve Milby
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5895 Posts

Response Posted - 04/03/2008 : 10:20:14

I know the conventional wisdom among racers is to lighten the boat as much as possible, and that's what your logic would ordinarily tell you, but that logic doesn't hold true with some sailboats, as it does with automobiles, for example. It depends on all the conditions. There is really one main reason to lighten the boat - to enable it to surf more easily. If a sailboat can surf, it's speed increases dramatically. That's crucial for racing boats that are designed to surf easily, such as Js, but it usually doesn't mean much for a family cruiser, like a C25, which is heavy and only surfs in ideal conditions. A lighter boat accelerates more quickly, but, the other side of the coin is that it doesn't coast as far, so that isn't an important reason to lighten it.

On the other hand, it's usually very beneficial to carry extra weight, especially in the form of movable ballast (crew) in especially light air or in strong winds. In light air (near drifting conditions) you can put your crew on the leeward rail to keep the boat moving when other boats are sitting still, with slatting sails. Dinghy racers do that all the time, but, on a bigger, ballasted boat it takes more crew weight to induce it to heel enough to achieve the desired effect. In strong winds, you can keep the boat on its feet by putting crew on the windward rail. In moderate winds, you don't need extra crew to either keep the boat on its feet, or to keep it moving.

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JimB517
Past Commodore

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3285 Posts

Response Posted - 04/03/2008 : 17:56:55

I know one thing, when I load about 1000 lbs on the boat for a 3 week long cruise the ride in chop is remarkably better.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/03/2008 : 18:41:21

...as is the momentum that carries you through the chop up-wind. But that's offset to some degree by the greater force required to accelerate back to speed when wave does slow you down or when you tack. For long distances, weight can be a good thing--a slight disadvantage off the wind, and helpful into it. The fact that your list didn't change when you emptied the tank suggests to me that the full tank isn't going to change your overall performance on the open ocean.

Edited by - Dave Bristle on 04/03/2008 18:42:48

Steve Milby
Past Commodore

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5895 Posts

Response Posted - 04/03/2008 : 19:58:05

To the extent that the older models persistently list to port, that was a design flaw. Those sailboats don't point quite as high on one tack as on the other tack. But, the boat was designed back in the days when the ordinary 2 cycle outboard motor, mounted on the port side, only weighed about 70 pounds, and the weight of a tank full of water on the starboard side was sufficient to even out the trim of the boat. The modern 4 cycle motors, weighing as much as 100 pounds or more, add so much weight to port that the weight of a tank full of water to starboard isn't enough to trim it out. The fact that it's out of trim is going to detract from the boat's performance, so, filling the tank will help, but it won't be enough to correct the list to port. The best remedy would be to do what many owners of the older C25s have done, i.e., relocate the motor mount to the starboard side, and perhaps carry a little extra ballast, if necessary, to fine trim the boat. The old mounting holes could be filled and covered with a decal with the boat's name. The effect on the boat's performance probably wouldn't be enough to bother most cruising sailors, but it would annoy the heck out of a racer, who knows he's losing a fraction of a fraction of a knot per hour.

Edited by - Steve Milby on 04/03/2008 20:01:45

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 04/04/2008 : 13:26:09

Last night I sailed in about 15 knots of wind gusting higher and a rough, choppy, ocean with waves about 4 feet. The boat is at least 200 lbs lighter, with 50 of that out of the bow. She seemed much more lively, popping over the waves and slamming down hard rather than cutting through them. I only had my 110 and full main up, I think the boat would have been a little better powered under the 135.

Was she faster? Hard to say. A similar sized boat on the way out way out pointed me and was about 1/2 knot faster but if I had my 135 up I probably would have kept up.

I'm going to get a little more weight off and loosen my rigging a little - I have everything pretty tight for strong winter winds and rough seas.

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Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 04/22/2008 : 12:22:30

In Normal conditions drain the tank and balance it out with your batteries and anchor. Ready to deploy doesn't necessarily mean in the anchor locker. We always raced as light as possible in moderate wind and minimal waves. If the rules allowed 1 cushion and no table, that is what we went with.

In lumpy heavy air conditions put your sails, your cushions, spare anchor and crew gear midline to bring your bow down. If your allowed to remove the outboard, put that down there too.

In light air , put the dogs in the house - forward to the bulkhead and on the high or low side as applicable. That should bring bow down and help minimize the chop.

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