Wind speed

Sanman · Jan 2, 2010

I have been thinking about this as well... I have a Hunter 26 and after out trip in the Med on a 45' I would like to have a masthead wind instrument as well... Being cheap, I found a Weather station with wireless transmitter at Home Depot and am considering this as an alternative.mounting the wind unit above my forestay (fractional rig) and having the base either in the cockpit or down below but visible... maybe a swing out mount?
Since I dont leave my boat in the water, and the unit is under a Boat buck...I'm thinking it may be an alternative... Anyone have any thoughts on that idea?

Joe · Jan 3, 2010

Sanford H. said:
I have been thinking about this as well... I have a Hunter 26 and after out trip in the Med on a 45' I would like to have a masthead wind instrument as well... Being cheap, I found a Weather station with wireless transmitter at Home Depot and am considering this as an alternative.mounting the wind unit above my forestay (fractional rig) and having the base either in the cockpit or down below but visible... maybe a swing out mount?
Since I dont leave my boat in the water, and the unit is under a Boat buck...I'm thinking it may be an alternative... Anyone have any thoughts on that idea?

Yeah, give it a try and tell us how it worked out. Uhmm.... are there batteries in the transmitter?

Quoddy · Jan 4, 2010

All wireless?

Got a wireless for home use for Christmas. Looks like the anemometer is hard wired, other sensors in the package are wireless.

Don Guillette · Jan 4, 2010

Sanford: The wind speed at the top of a 45' mast blows 50% to 60% harder than at deck level. The reason for that is friction. As the wind blows across the surface of the water it is forced to slow down. So the wind you feel on your face or the back of your neck is not what is going on at the top part of your main and jib.

This difference in wind speed is one of the reasons the sail makers build twist into the top of the sails. If they didn't you would not be able to control the boat - you'd be over on your ear. The twisted part of the top of the main and jib allows some of the increased wind speed to bleed off. Twist is a very important element of sail trim. Knowing what twist is all about and how to use it is obviously very important.

If a sailor does not understand draft depth, draft position, twist and angle of attack, sail trim will never make any sense.

Scott T-Bird · Jan 4, 2010

Twist for sailing excellence ...

I think that the application of twist is confusiing based on the way sailors descibe the function of twist. Many say that you ae 'depowering' by increasing twist. It is true that a sail shape with too little twist may cause excessive heeling, and a feeling of being over-powered. But isn't it true in that circumstance that you are actually increasing sail effeciency, and speed, and power, when you increase twist to the optimal shape? It is when you increase twist beyond the optimal shape that you are actually 'depowering' the sail. This may be effective to maintain better control when your sail plan has a little too much sail area.

I know from my windsurfing experience (where sail shape has a much more dramatic effect on sail control) that you will feel very over-powered (and sluggish) if you have too little twist, you will feel power and control with just the right amount of twist, and you will feel less power (helpful sometimes when the wind is strong) but very squirrelly when over-twisted. Twist is controlled by downhaul in the case of a windsurfing rig because the mast bend is increased and the leach is loosened. Draft depth is controlled by outhaul as on a sailboat, except that for many camber-induced sails, you leave the outhaul neutral (no tension at all) and the draft depth is more or less constant with adjustments made most effectively with downhaul.

Don Guillette · Jan 4, 2010

I’m really not sure where to start here so let’s start with the terms we are using so we are on the same page. Opening or increasing twist means the top 1/3 of the main or jib is leaning outwards. Closing or decreasing twist means we are flattening the top 1/3 of the main and jib so it is more in line with the leech.

Twist, draft depth, draft position and angle of attack all have to work together or the boat does not perform to 100% efficiency. The boat may move through the water when these 4 elements are out of balance but it won’t be efficient.

For each point of sail and wind condition there is a set adjustment for each of the 4 element and the purpose of the sail trim controls for the main and jib are there to set that balance. Sail trim is a balancing act. Too much or too little is not a good thing.

Twist is NOT controlled by the downhaul (Cunningham) or halyard. Those sail trim controls are used to adjust draft position. The primary mainsail twist control is the boom vang and the secondary mainsail twist control is the mainsheet. You can crank on the downhaul all day long and it will have no effect on twist. All your doing is messing with the luff of the sail when it is the leech you should be dealing with.

Draft depth is controlled by the outhaul but you have to be careful with the outhaul because it is also one of the sail trim controls for draft position.

This is for all forum listers – if you want to be any good at sail trim you have to completely understand draft depth, draft position, twist and angle of attack. If you don’t have that understanding sail trim will never make any sense. Next you have to know WHICH sail trim controls for the main and jib used to adjust those 4 elements. Once you get to that point you are ¾ of the way to being a good sail trimmer.

How do you get the above info? Well, you could look it up but I’ve already done that for you. I provide a free “quick reference” with every SAIL TRIM CHART which outlines which sail trim controls for the main and jib are used to adjust the 4 elements of sail trim. The first chapter of the SAIL TRIM USERS GUIDE explains the 4 elements of sail in plain English – so even I can understand it.

Scott T-Bird · Jan 4, 2010

Don ...

I was describing the effect of downhaul and twist on a windsurfing rig ... not on a sailboat. I have your trim guides and I know how to establish the right amount of twist on my sailboat.

Actually, on a windsurfing rig with camber-induced sails, you can position the draft (fore and aft and depth) with the tension of the battens (not the outhaul, which is often neutral). My North Sails have a little cam adjustment that you use to micro tune each of the battens, adjusting draft depth and position. These are old sails though, so the technoloy has surely changed. This gets into some very fine tuning, but like I said, a windsurfing rig is far more sensitive to sail trim (in feel to the human touch) and the difference between millimeters in all the trim adjustments is the difference between a sail that is a dog and the same sail that blasts right by all the others on the water.

Don Guillette · Jan 4, 2010

Re: Don ...

Scott: I've never been on a windsurfer but I would watch them in an area in Long Beach Harbor, Ca called Hurricane Gulch. These guys and gals were very, very good. They amazed me and i wanted to try it. Later, at Lake Havasu, AZ I stumbled on a guy giving windsurfer classes. We became friends and I ended up buying a pristine Mac22 from him. Our reason for buying the Mac22 was my wife and I were sick of our children bringing our jet boat back in pieces and we decided to get back into sailing. Anyway, I just could not get the hang of it. I could not stand up on the dang thing. Finally my friend gave up on me but I spent many hours on the beach watching others sail those things and it gave me a good education of the effect of wind on the sails and how important sail trim is. I knew what they were doing even though I could not do it myself.

Thanks for buying my products and anyone who has a wife as pretty as yours can't be all bad!! Thank you for contributing to the sail trim forum.