Brian,
I don’t know if the firehose of advice flowing in will help or hurt in acclimating to the firehose of water that comes in when changing knotmeter plugs. For some reason, I can’t resist thowing in my $0.015 in (the ordinary two cents is discounted to reflect the quality of the advice).
Personally, I hate simply dealing with the mess that has to be cleaned up after all that water comes in.
A number of people have pointed out that the knotmeter is more responsive than the GPS, and that it measures speed through the water vs. speed over ground. IMHO, the choice of which to rely upon is important for racing and navigation, but less critical when the goal is familiarizing yourself with a boat and the effects of different courses and sail trim. In playing with factors to improve speed, relative increases or decreases observed on either are sufficiently informative.
Because of leeway, a GPS’ speed over ground is not the same as speed in the direction the boat’s pointing. Because of currents that can be helping or slowing a boat, a knotmeter’s speed through the water may not match its speed over ground. It’s kind of similar to the difference between true and apparent wind.
One can spend a lot of money on instruments that give you more exact information. Or, as I got taught in coastal piloting classes some 40 years ago, do calculations. If you’re trying to navigate to a distant destination you can’t actually see, or trying to decide the best course to win a race, it matters a lot more than if you’re just out trying to have a nice day.
The manuals for all of our boats include a page illustrating where the lifting slings should go. I always give a copy of that to my yard, in addition to having put markers on the rail at each of those points. It’s not just about the paddlewheels. Those points correspond to interior structures that reinforce the hull against the point pressures exerted by the slings, as well as reflecting where the boat should balance well.
In our Southern California waters, it’s far more likely that paddlewheels get broken by some combination of aged devices and the divers we all hire to clean our boat bottoms rather than by the liftout slings. In fairness to the divers, it’s hard to tell the difference between stubborn marine life surrounding a paddle and stubborn marine life not surrounding one, so they tend to treat them the same.
My take on the question of, “I’m trying to understand how the stalled leech TTs relate to the weather helm. Do they warn of it or are they just an interesting side effect?” … My answer is, yes, it’s a warning, but only sort of.
Stalled leech telltails wrapped around the outside edge of the sail indicate that the airflow is not moving smoothly over the sail but instead is pushing more on its aft end. Because the air is pushing more on the back of the sail than it should, the center of effort has moved further back than ideal. This, in turn, means that it’s pushing the sail in a direction that would cause it to turn into the wind more than the keel is designed to counter. That means (if you don’t ease the main) you have to use the rudder to counter that push. If that push is too great, the rudder has to turn more to counter it. So, yes, then you could call that weather helm in the sense the rudder’s excess angle is creating drag.
The “sort of” part of my answer comes from the fact that our boats are really, really forgiving. Consequently, the leech telltails will stall long before you rally feel that drag. If you’re trying to squeeze the last drop of speed out of the boat, you’ll want to watch them and adjust long before the rudder and wheel gives you any feedback. If you’re just concerned about making adjustments before the boat gets hard to control, the telltails are a way too early warning system – like wearing a sweater today because the barometer told you it’ll be cooler tomorrow. So, technically, stalled telltales are a precursor to weather helm. But not a very useful warning of it.
Note that I may be defining weather helm differently than you. A well-designed boat in motion is supposed to exhibit some degree of weather helm in the sense of a tendency to turn into the wind unless rudder is applied to correct it. That slows and stops it if the helmsman goes overboard. Our boats tend to fall off rather than stay pointed into the wind once they slow. That’s one sense of weather helm.
That sense of weather helm is good. The point where weather helm becomes bad is actually better understood as drag. If the rudder is over-applied to turn the boat, it’s turning the boat not because of the water flowing over it but because it’s acting as brake. The rudder stops keep it from going perpendicular to the boat, so its shape puts more of the rudder on one side than the other – turning the boat but also slowing it. When the interest is maximizing speed, it’s actually drag rather than weather helm that’s at issue. Until the forces get too strong.
The next sense of weather helm is referring to when the boat gets out of control. When the forces on the sail get too great, the boat will want to pivot around the mast no matter what the keel and rudder are doing. At that point, the only way to get back under control is to reduce those forces by reefing. Since that’s easier done in anticipation than after you’ve lost control, people look for the best way to anticipate.
Some use wind speed rules (reef at X kts.), some use heel angle (reef at Y degrees). I prefer to use some combination of rudder feedback (reef if the rudder’s fighting you more than you feel like dealing with) and the principle of happy camper crew management (reef as soon as anyone on board looks nervous). Details depend on how I feel on a given day, and how much I want my guests to keep coming back.
As I said, my $0.015, discounted from 2 cents to reflect the value of the opinions.
– Bob
Me Gusta
Nonsuch e26U #233
