This is such an educational thread. It's better than a chapter in a top technical manual on sail trim, because you get to read some back and forth on different points and points of view.
My take, for the purposes of OP's original question, is that a properly tuned mast head rig with a fin keel should be just a little loose. Helm is determined by balance around the center of lateral resistance (CLR) and fin keels are more sensitive to that balance.
Tightening the luff of a sail helps depower that sail so by tightening the backstay of a masthead sloop you end up depowering the jib but not the main. This results in less lift ahead of the CLR while the lift of the main, behind the CLR, remains the same. This increases weather helm. To improve the balance when there is too much weather helm, one would want to depower (reduce lift on) the main while either increasing or holding the power of the jib. That means tightening the main luff with either the halyard or a cunningham or the downhaul and the outhaul. Tighten the vang. Move the traveler out, but tighten the main sheet. These are all things to experiment with to get your best trim for you and your boat.
I disagree with the statement that rake is not for beginners to play with. This is basic rig tuning for a boat owner to learn and understand. It is set when the boat is setup at launch and not typically played with under sail by anyone no matter their experience. There aren't too many boats with dynamically adjustable forestays. If you have played with the trim of your boat and can't get it to sail with the right balance by use of the above mentioned controls, setting the rake to move your balance a little forward or aft may be the answer. There is, however only a few inches to a foot or so of tolerance to play with by this method. Good dynamic sail trim is still called for.
As for the squatting under auxiliary power, throttle back. Once a displacement hull reaches "hull speed", the wake is equal in wave length to the waterline length and your vessel should be level while riding through the water. As you increase power, your increase in speed lengthens the wake even longer and your bow is on top of the bow wake while your stern slides further and further down the stern wake as it gets farther behind. This effectively translates to you trying to chug uphill and that uses an exponential increase in power. The extra speed will hardly be worth the fuel consumption and wear on the engine.
Note, in shallow water, where the displaced water can't move down as well as out to get out of the way of the moving hull, you can also experience a drag on and squatting of the hull as your wake gets steeper than normal. The bottom almost feels like it sucks the boat down. Try it in a kayak. Paddle as fast as you can along a shore. Move in to shallow water, then out to deep water. You can feel the difference.
-Will (Dragonfly)
My take, for the purposes of OP's original question, is that a properly tuned mast head rig with a fin keel should be just a little loose. Helm is determined by balance around the center of lateral resistance (CLR) and fin keels are more sensitive to that balance.
Tightening the luff of a sail helps depower that sail so by tightening the backstay of a masthead sloop you end up depowering the jib but not the main. This results in less lift ahead of the CLR while the lift of the main, behind the CLR, remains the same. This increases weather helm. To improve the balance when there is too much weather helm, one would want to depower (reduce lift on) the main while either increasing or holding the power of the jib. That means tightening the main luff with either the halyard or a cunningham or the downhaul and the outhaul. Tighten the vang. Move the traveler out, but tighten the main sheet. These are all things to experiment with to get your best trim for you and your boat.
I disagree with the statement that rake is not for beginners to play with. This is basic rig tuning for a boat owner to learn and understand. It is set when the boat is setup at launch and not typically played with under sail by anyone no matter their experience. There aren't too many boats with dynamically adjustable forestays. If you have played with the trim of your boat and can't get it to sail with the right balance by use of the above mentioned controls, setting the rake to move your balance a little forward or aft may be the answer. There is, however only a few inches to a foot or so of tolerance to play with by this method. Good dynamic sail trim is still called for.
As for the squatting under auxiliary power, throttle back. Once a displacement hull reaches "hull speed", the wake is equal in wave length to the waterline length and your vessel should be level while riding through the water. As you increase power, your increase in speed lengthens the wake even longer and your bow is on top of the bow wake while your stern slides further and further down the stern wake as it gets farther behind. This effectively translates to you trying to chug uphill and that uses an exponential increase in power. The extra speed will hardly be worth the fuel consumption and wear on the engine.
Note, in shallow water, where the displaced water can't move down as well as out to get out of the way of the moving hull, you can also experience a drag on and squatting of the hull as your wake gets steeper than normal. The bottom almost feels like it sucks the boat down. Try it in a kayak. Paddle as fast as you can along a shore. Move in to shallow water, then out to deep water. You can feel the difference.
-Will (Dragonfly)
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