Generic "Fantail" sail planform drawing

  • 30 Dec 2012 21:15
    Reply # 1168971 on 1168934
    Gary Pick wrote:Could someone explain the the significance of David's factor of 1.562 please?
    My sail is about 30.32 sq metres and if I use that factor I get a LAP of 8.6 which means my mast is nearly a metre short!
    My sail is the same design as Arne's.
    Gary, it's just a factor used to calculate the LAP length for a "Fantail" type sail of certain proportions. You do not need to be concerned, it has no bearing on your sail. The fact that you have a shorter mast, just means that should you ever want to put a "Fantail" type sail on your boat, it would have to be a lower aspect ratio sail than the one under discussion.
  • 30 Dec 2012 18:17
    Reply # 1168901 on 1060993
    I have Gary's sailplan which is 32.5 sqm, good looking sail. I have checked the diagonals as per PJR and it will reef and furl perfectly. The problem is that the distances between battens on the leach are all different and will give rise to sheeting issues. Given my experience with Pacific Spray in this regard I want the sheeting to work out from day one. 
  • 30 Dec 2012 17:23
    Reply # 1168883 on 1168736
    Robert Prince wrote:Thanks Paul. 
    I was looking at 32.5 sqm for the sail, so the square root of that times David's factor of 1.562 gives an LAP of 8.9 metres. Seems to make sense as the sailplan I have from the designer, which is very low profile, calls for an overall mast length of 8.9 metres which is LAP plus the bury. 

    Yes, that sounds right. Have you received a sailplan from Gary yet?
  • 30 Dec 2012 06:20
    Reply # 1168736 on 1060993
    Thanks Paul. 
    I was looking at 32.5 sqm for the sail, so the square root of that times David's factor of 1.562 gives an LAP of 8.9 metres. Seems to make sense as the sailplan I have from the designer, which is very low profile, calls for an overall mast length of 8.9 metres which is LAP plus the bury. 
  • 30 Dec 2012 04:42
    Reply # 1168723 on 1168716
    Robert Prince wrote:One question - what is LAP? 

    Length above partners - essentially the measurement from deck to masthead but not necessarily so as the partners can be raised above the deck (as in LC for example).
    Last modified: 30 Dec 2012 17:21 | Anonymous member
  • 30 Dec 2012 04:13
    Reply # 1168716 on 1060993
    We are moored, on Pacific Spray, in Tutukaka at the moment on our way north to the Bay of Islands junket. Its been raining all day so I started reading Kurt's article on flat sails. Well done, Kurt. After that inspiration I moved onto PJR and the Fantail generic sailplan as an option for Shoehorn, and although its not easy to put it all together in my head we are all lucky to have such fine resources. One question - what is LAP? 
  • 21 Dec 2012 19:06
    Reply # 1164864 on 1164705
    Jeff McFadden wrote:

    I will have some rake, probably 4 or 5 degrees, just to keep the sail swung out in light and fluky winds, but the plan is to be able to build a proper junk sail and have it fit sensibly on the mast.
    I've come to the view that 4 degrees forward rake is optimum for this sail shape, +/- 2 degrees, so as long as the helm balance works out right, Seablossom will be happy with this.
  • 21 Dec 2012 18:47
    Reply # 1164850 on 1060993
    That all sounds good and should work out well. Footprints has 3 degrees of rake and the sail sits very well on the mast, Tystie I think has 2 degrees and Fantail 6 degrees so there seems to be plenty of room for variables. It will be a matter of making sure you get the Centre of Effort of the sail in the right place. With the sails on Footprints and Tystie we also have the ability to swing the sail across the mast for off the wind work which helps to minimise any weather helm that develops as the sail powers up. The fan shaped sails look very pretty and seem to be a good option for a single sail rig.
  • 21 Dec 2012 14:20
    Reply # 1164705 on 1164450
    David Thatcher wrote:David Tyler may correct me on this but based on my experiences with the new Fan shaped sail on Footprints, and the photo of your boat rigged with the current sail where you have a lot of sail forward of the mast, you may experience problems with a fan shaped sail with the mast in its current position. Because a fan shaped sail is fairly low aspect it can put the CE well aft. You may need to look at raking your mast forward a substantial amount. This is what I had to do to Footprints to get the sail working properly, and thankfully it has now been a total success, but not without a lot of work.

    I've been gone for a long time and it's no surprise that it's not obvious, but the very first step of this process has been moving the mast well forward, from the middle of the cabin to the foredeck forward of the coach roof. I have cut the hole in the deck for the partners but I have not yet built the step.
    I will have some rake, probably 4 or 5 degrees, just to keep the sail swung out in light and fluky winds, but the plan is to be able to build a proper junk sail and have it fit sensibly on the mast.
  • 21 Dec 2012 04:41
    Reply # 1164450 on 1060993
    David Tyler may correct me on this but based on my experiences with the new Fan shaped sail on Footprints, and the photo of your boat rigged with the current sail where you have a lot of sail forward of the mast, you may experience problems with a fan shaped sail with the mast in its current position. Because a fan shaped sail is fairly low aspect it can put the CE well aft. You may need to look at raking your mast forward a substantial amount. This is what I had to do to Footprints to get the sail working properly, and thankfully it has now been a total success, but not without a lot of work.
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