Interesting comments

[Guest Rocket]

Hate to sh*t on the usual leebow theory (not) but - we sail in apparent wind. The apparent wind is a combination of actual wind (relative to ground) , tide direction and boatspeed. Draw single line vectors.... and you can work out the apparent wind. So if the boat is stopped the apparent wind is just current plus true wind which is he same wherever you point.... (So I am a Dave Perry believer)

 

When in strong current you are effectively sailng on an escalator (relative to the ground). Of course strong tide taking you to windward affects the VMG - again use the vectors. And yes if you want to get around a mark (anchored to the ground) and you park the boat (relative to the water) and let the escalator do the work you will get there. But this isn't what people generally imagine is lee bowing they seem to think it has a mystical property (it doesn't it is all simple physics). So sometimes it makes sense to sail high and slow to stay in the stronger (positive) tide longer other times it pays to sail low and fast get out of the stronger (unfavourable) tide faster. The so called lee bow effect is no more than that... Downwind the apparent wind (when tide is running across the course) will give you better pressure on one gybe (as it help maintain the flow), but teh apparent wind is the same on either gybe if you stop the boat!. In some boats (like a laser) when flat running this is back to front from boats with spinnakers as you sail lasers by the lee with the flow going from leach to luff... But if you think in the net vector of the three forces (i.e. the apparent wind) you will get it.

 

Different speed on different tacks is usually down to whether the rig is square in the boat - you will sometimes see your mainsail setting up very differently upwind when the rig isn't right.. Another cause is waves on an angle to the wind (pounding on one tack).

[Guest]

Of course the waves would have a big effect. That explains why faster on one tack than another better than the current (tidal flow) theory. Even just the chop would have an effect.

Yes definitely leaning towards the wind instrument. Safety stuff is so boring while I'm safe.

[PaulR 3]

No problems, a pleasure. We have all struggled getting our heads around the new technology now so cheaply available.

 

In the last Simard 100, I had both VMW on the GPS and VMG on the speedo and boat speed as was comparing all three.

[Guest]

Hope KM dosn't mind us pinching his thread. Especially as for gps.