Posted by peteryoungman (peter.youngman@…>)
Hi everyone.
The boat is now stripped out and ready for repaint etc. Fit out to be
as simple as possible.
I will be replacing my lifting bilge leels.
Does anyone have any thoughts on whether they can be improved. I
wonder specifically whether the drag when they are raised, when
sailing off the wind, is really off set by increased performance to
wind ward.
Any thoughts on which keel to lower, leeward or wind ward when
beating.
Counter intuitively if wind ward keel is lowered then there is a
greater turning moment, if the wing on the keel were then to turn
inboard the effective depth would be increased and I wonder about the
pressure difference, does it/would it act to windward?
If any one is talking to Garry Hoyt I would be very interested in his
opinion.
Peter Youngman
Posted by Wilf Bishop (wilf.bishop@…>)
HI Peter,
I do not bother to host/lower my twin lift keels when sailing since raising the ballast keels must have some detrimental effect on stability and in any event I find the lift keel F21 to be rather “tender” at her mooring in heeling terms but somehow “stiffer” and more stable when under way? I’m sure that there is some complex bit of naval architecture to explain this - form stability or something similar - but having sailed both the normal fin keel and Warwick-Collins wing keel versions I find them both to have less initial “tenderness” than the twin lift keel F21. Hence I would be nervous sailing with one or both keels lifted - particularly since we get some really hairy sudden katabatic winds blowing down the mountain side valleys up at Ullswater? In fact a lift keel Parker 21 was completely inverted a few years ago in such a blast where the lift keel partly sliced through the inverted cabin roof. In these sailing conditions its good to have the F21 swift reef system ready to hand.
I understood from the MD of the last company who built the F21 in the UK (St Olaves Boatbuilder - Great Yarmouth) that Mr Hoyt was never a great fan of the twin lift keel version which evidently was the brainchild of John Oakley’s. So I guess that John would be the best authority on the pros & cons of the twin lifting keel modification?
For my part I just lower the keels at the start of the sailing season when Daydream gets put on her mooring and the only time the keels come up is if we nose into a shallow bay for a picnic - otherwise they stay down until hauling-out day in October. If you decide to evaluate the merits of keel juggling under way let us know how it goes?
Best regards
Wilf Bishop
F21 Daydream
----- Original Message -----
From: peteryoungman
To: freedom21@yahoogroups.com
Sent: Wednesday, October 11, 2006 1:20 PM
Subject: [freedom21] Lifting bilge keels F21 Suffolk UK
Hi everyone.The boat is now stripped out and ready for repaint etc. Fit out to be as simple as possible.I will be replacing my lifting bilge leels.Does anyone have any thoughts on whether they can be improved. I wonder specifically whether the drag when they are raised, when sailing off the wind, is really off set by increased performance to wind ward. Any thoughts on which keel to lower, leeward or wind ward when beating.Counter intuitively if wind ward keel is lowered then there is a greater turning moment, if the wing on the keel were then to turn inboard the effective depth would be increased and I wonder about the pressure difference, does it/would it act to windward?If any one is talking to Garry Hoyt I would be very interested in his opinion.Peter Youngman