Don, My H35.5 sails faster on a Starboard tack than on a Port tack, speed measured both on GPS and boat speed. I have tuned the fractional rig (straight mast, rake, etc.) according to Brion Toss video. Do I have to add more shroud tension on one side than the other? Any ideas? Thanks. Ozana
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Speedo differences - a hydrodynamic anomaly
If your paddlewheel is mounted offset from the centerline, the flow across the wheel will not be the same on both tacks - hence the difference in speed that you notice on different tacks. With the paddlewheel not 'mounted on the centerline' the 'sideways' slip of the hull will affect the speed of the 'wheel' .... more when slipping 'into' the wheel and less when slipping 'away' from the wheel. So, if your paddlewheel is not exactly on the centerline and is 'anywhere near' the leading edge of the keel ... expect the readings to be very different when the boat is heeled and on different tacks.
If your paddlewheel is mounted offset from the centerline, the flow across the wheel will not be the same on both tacks - hence the difference in speed that you notice on different tacks. With the paddlewheel not 'mounted on the centerline' the 'sideways' slip of the hull will affect the speed of the 'wheel' .... more when slipping 'into' the wheel and less when slipping 'away' from the wheel. So, if your paddlewheel is not exactly on the centerline and is 'anywhere near' the leading edge of the keel ... expect the readings to be very different when the boat is heeled and on different tacks.
ok here is a way to measure it better
First of all balance the boats load. make sure the boat has perfect balance front to back and side to side. a few pounds on many boats will make it heal a degree or two. thus different speed different tack. then put a speed transducer on each side of the boat so you can measure the speed on the low side of the hull. and away from foils. this can be done with a mercury swith on a lever that switches the transducer to read low side. now accurately measure all rigging. many boats not a few, have masts set as far as 4 or 5 inches off the centerline. this is done to allow access and egress, for instalation of doors hatches or other equipment. measure all rigging to ensure consistant lengths, check mast to ensure it is plumb in the boat. the go check the prop. if you have a folder you have to ensure the blades are closed not dangling off to one side or the other, if it two bade make sure it is straight up and down or if its three blade you can do much. it the shaft is offset( many are then you have to just tube it because the drag is not even. now its time to tune the rig, to ensure that all loads are equal on the mast and rig. Now you can go sail and check it. If the boat is a perfect hull, as is perfectly semetric in every which is not possible in most boats especially larger ones, ( fiberglass and wood flex and adapt to loads. slightly that is but the move). that may cover about 1/2 the reasons for the problem. almost all boats preform differently on different tacks. thats just reality.
First of all balance the boats load. make sure the boat has perfect balance front to back and side to side. a few pounds on many boats will make it heal a degree or two. thus different speed different tack. then put a speed transducer on each side of the boat so you can measure the speed on the low side of the hull. and away from foils. this can be done with a mercury swith on a lever that switches the transducer to read low side. now accurately measure all rigging. many boats not a few, have masts set as far as 4 or 5 inches off the centerline. this is done to allow access and egress, for instalation of doors hatches or other equipment. measure all rigging to ensure consistant lengths, check mast to ensure it is plumb in the boat. the go check the prop. if you have a folder you have to ensure the blades are closed not dangling off to one side or the other, if it two bade make sure it is straight up and down or if its three blade you can do much. it the shaft is offset( many are then you have to just tube it because the drag is not even. now its time to tune the rig, to ensure that all loads are equal on the mast and rig. Now you can go sail and check it. If the boat is a perfect hull, as is perfectly semetric in every which is not possible in most boats especially larger ones, ( fiberglass and wood flex and adapt to loads. slightly that is but the move). that may cover about 1/2 the reasons for the problem. almost all boats preform differently on different tacks. thats just reality.
What is the differential?
The speed difference, if it is small, could be the result of small differences in shape port and starboard. Does you crew change places from one tack to the next. Is someone draging their feet?
The speed difference, if it is small, could be the result of small differences in shape port and starboard. Does you crew change places from one tack to the next. Is someone draging their feet?
had this last year
Hello, I had the same problem last year. My boat was about .5 kt faster on a port tack. I was repeatable in all conditions. I checked the rigging and it was not tuned properly. I corrected it (need to slack the port side and tension the starboard. Now my boat is the same on both tacks. Barry
Hello, I had the same problem last year. My boat was about .5 kt faster on a port tack. I was repeatable in all conditions. I checked the rigging and it was not tuned properly. I corrected it (need to slack the port side and tension the starboard. Now my boat is the same on both tacks. Barry
Mast off center!
Ed, I am surprised by a portion of your answer. You say that several boats have the mast offset up to 4 or 5 inches to one side to facilitate access and egress, for instalation of doors hatches or other equipment. I always thought that boats were built around fixed parameters, one important one being mast on centerline. Could you name a few example of boats with these offset masts . Thanks in advance
Ed, I am surprised by a portion of your answer. You say that several boats have the mast offset up to 4 or 5 inches to one side to facilitate access and egress, for instalation of doors hatches or other equipment. I always thought that boats were built around fixed parameters, one important one being mast on centerline. Could you name a few example of boats with these offset masts . Thanks in advance
Wave direction
I have noticed that with my 35.5 as well but I don't believe we could ever get all the variables previously mentioned under control. The biggest difference I notice is that the wind and waves are not often coming from the exact same direction and the waves have a bigger impact on one tack or another. My boat has noticable list to starboard due to the batteries and it seems to be faster on that tack.
I have noticed that with my 35.5 as well but I don't believe we could ever get all the variables previously mentioned under control. The biggest difference I notice is that the wind and waves are not often coming from the exact same direction and the waves have a bigger impact on one tack or another. My boat has noticable list to starboard due to the batteries and it seems to be faster on that tack.
The difference in speed...
is about 1 knt, BOTH on the boat speed display and ont he GPS display. Current or no current, waves or no waves, Beer in the fridge or no beer on the fridge, It is always the same, faster on Starboar tack than on Port tack, also you can feel that it sails better on the Starboard tack. I guess I will try to-retune the rig.
is about 1 knt, BOTH on the boat speed display and ont he GPS display. Current or no current, waves or no waves, Beer in the fridge or no beer on the fridge, It is always the same, faster on Starboar tack than on Port tack, also you can feel that it sails better on the Starboard tack. I guess I will try to-retune the rig.
OZANA...
She sails better on starboard tack 'cause she knows she's privileged!!! Paul Pretty Lady
She sails better on starboard tack 'cause she knows she's privileged!!! Paul Pretty Lady
How are you measuring apparent wind angle
I have never seen a Windex set perfectly and if you have a electronic wind position indicator how was it calibrated. You may just be pinching too high on one tack. Wave direction can make one tack a lot slower.
I have never seen a Windex set perfectly and if you have a electronic wind position indicator how was it calibrated. You may just be pinching too high on one tack. Wave direction can make one tack a lot slower.
I think that his 1kt. differential in all
conditions and winds must relate to the alignment of the rig. A couple of tenths might be pointing and apparent wind but if his mast is out of plumb then the relative heeling is greater on one tack than the other. If this is the case he is spilling wind on one tack and loosing power.
conditions and winds must relate to the alignment of the rig. A couple of tenths might be pointing and apparent wind but if his mast is out of plumb then the relative heeling is greater on one tack than the other. If this is the case he is spilling wind on one tack and loosing power.
boats are not built perfect
Boats are not perfect. Keel could be a little off to one side or anything else. I have heard from a race guy who races this is actually very common. I just read an article about a hunter being built that they had a hard time getting the deck to to fit the hull. You would think molds would fit together. Nothing is square on a boat?
Boats are not perfect. Keel could be a little off to one side or anything else. I have heard from a race guy who races this is actually very common. I just read an article about a hunter being built that they had a hard time getting the deck to to fit the hull. You would think molds would fit together. Nothing is square on a boat?
Keel check
A one knot difference is huge! Do you happen to have any winglets on your keel? I've seen many Hunters with bent winglets due to groundings. You might want to check them the next time you haul the boat. One side might be bent and the other side just fine.
A one knot difference is huge! Do you happen to have any winglets on your keel? I've seen many Hunters with bent winglets due to groundings. You might want to check them the next time you haul the boat. One side might be bent and the other side just fine.
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