Forgot password

How does one sail a schooner to windward? (Touches on motor-sailing too.)

<< First  < Prev   1   2   3   4   Next >  Last >> 
  • 01 Nov 2013 12:39
    Quote
    Reply # 1425991 on 1417956
    Deleted user
    The leeches have telltales all over them. Problem is the main obscures the telltales of the foresail when beating, unless I crawl under the main boom to leeward, maybe I could get a glimpse.
  • 01 Nov 2013 07:24
    Quote
    Reply # 1425922 on 1417956
    Anonymous member (Administrator)

    Strictly on topic; here is another one:

    Fit telltales to the sails. I mainly fit them to the leech of each panel. That helps me to not over-sheet the sail. You may be surprised and find that you can sheet in the mainsail more than you thought, since you have a foresail in front of it. If there is a weather helm problem (there will always be, on a reach, at least), I would fit an end plate to the rudder to increase its lift with less drag. This may let you keep up full sails longer. More drive, less drag.

    Arne

    PS: Those telltales at the leech also help you check if the twist is right: If the telltales at the lower panels fall behind the sail much before those in the top (as you fall off without easing the sheets), then you have too much twist. I aim for a twist where all the telltales fall behind the sail at the same time.

    Last modified: 01 Nov 2013 07:48 | Anonymous member (Administrator)
  • 31 Oct 2013 23:26
    Quote
    Reply # 1425787 on 1425673
    Deleted user
    Brian Kerslake wrote:Guys, look back at the title of this thread - 'How does one sail a schooner to windward'? Tyros skim-reading it might think you have to turn the engine on :-) No time to shift all these motorboat posts into a thread of their own but let's try to stick to topics, eh?
    How about: sheet in the main more than the foresail and since the foresail does most the work to windward, reef the main deeper, this reduces drag.

    But should have titled this thread "Help, our schooner is slow, what happened?"
    Drag of an extra long shaft OB is what.
  • 31 Oct 2013 20:05
    Quote
    Reply # 1425673 on 1417956
    Deleted user
    Guys, look back at the title of this thread - 'How does one sail a schooner to windward'? Tyros skim-reading it might think you have to turn the engine on :-) No time to shift all these motorboat posts into a thread of their own but let's try to stick to topics, eh?
  • 27 Oct 2013 17:24
    Quote
    Reply # 1422328 on 1422315
    Anonymous member (Administrator)

    Looks like we're going down the right track building this OB lifting device. Could have tested the boat without the OB in the well first, but probably would have fallen overboard man handling it with the sails up..


    Gary, it's probably a good idea anyway. I don't think that outboards have been made to sit permanently in the water, although they are much better protected against corrosion these days...

    Arne

    PS: All my boats have had outboard engines, but I have always been careful to haul or swing them up when sailing. Now it seems there is another thing for me to check: In a steady downwind, I will record our speed and then lower the engine and record the speed again, both with the propeller stopped (in gear) and with it spinning freely.

    Last modified: 27 Oct 2013 21:54 | Anonymous member (Administrator)
  • 27 Oct 2013 16:54
    Quote
    Reply # 1422315 on 1422297
    Deleted user
    Arne Kverneland wrote:
    Gary King wrote:Yes but your prop has 9" pitch vs ours with 6", more like a disk shaped sea anchor!
    I think the drag is worse in heavy winds (proportional to speed^squared), since the boat rarely got above 4.5knots on a broad reach in 25 knot wind.

    Hm, I wonder about that, Gary.

    I thought that parasite drag from propellers etc. did most harm at low speed. The reason is that hull (wave) drag is very low below 4kts so parasitic drag (skin friction and propellers) then counts for a higher portion of the total drag. In my experience, drag from a foul bottom does more harm to the upwind performance where the horsepower output of the rig is the least. See here: In this write-up, tacking upwind was slow with a dirty bottom, but downwind we went over 6kts, just about as normal. My interpretation of that experience could be wrong, though…

     Hmm, my thinking on this is that an actual sea anchor imposes a "top speed" on a hull.

    Another thing: You mention that your propeller “pokes a long way out of the hull”, when down. That is well and fine when you motor. However, this could possibly increase the drag when you sail, as the propeller then sits in “clean water”, well outside the 10 – 20cm  thick boundary layer. The water inside the boundary layer moves more or less along with the hull, and the further aft on the hull, the thicker the boundary layer is. Graham’s big propeller may produce less damage for its size because it is closer to the hull, way aft of a long keel, and is thus partly hidden inside this boundary layer.

    This is where a prop sitting too far from the hull is like a sea anchor but different to a dirty bottom. So I stuffed up by having the prop sit 25cm below the hull.
    At least the boat performs above expectations while motoring. 4.5knots for a little 6hp on 35' boat. 

    Looks like we're going down the right track building this OB lifting device. Could have tested the boat without the OB in the well first, but probably would have fallen overboard man handling it with the sails up..
  • 27 Oct 2013 16:20
    Quote
    Reply # 1422297 on 1422029
    Anonymous member (Administrator)
    Gary King wrote:Yes but your prop has 9" pitch vs ours with 6", more like a disk shaped sea anchor!
    I think the drag is worse in heavy winds (proportional to speed^squared), since the boat rarely got above 4.5knots on a broad reach in 25 knot wind.

    Hm, I wonder about that, Gary.

    I thought that parasite drag from propellers etc. did most harm at low speed. The reason is that hull (wave) drag is very low below 4kts so parasitic drag (skin friction and propellers) then counts for a higher portion of the total drag. In my experience, drag from a foul bottom does more harm to the upwind performance where the horsepower output of the rig is the least. See here: In this write-up, tacking upwind was slow with a dirty bottom, but downwind we went over 6kts, just about as normal. My interpretation of that experience could be wrong, though…

     

    Another thing: You mention that your propeller “pokes a long way out of the hull”, when down. That is well and fine when you motor. However, this could possibly increase the drag when you sail, as the propeller then sits in “clean water”, well outside the 10 – 20cm  thick boundary layer. The water inside the boundary layer moves more or less along with the hull, and the further aft on the hull, the thicker the boundary layer is. Graham’s big propeller may produce less damage for its size because it is closer to the hull, way aft of a long keel, and is thus partly hidden inside this boundary layer.

     

    Just a thought...

    Arne

    Last modified: 27 Oct 2013 16:29 | Anonymous member (Administrator)
  • 27 Oct 2013 09:36
    Quote
    Reply # 1422075 on 1417956
    Anonymous member
    4.5knots on a broad reach in 25 knots of wind certainly indicates that you have a real issue here.  I'd estimate you should be sitting on 6 - 7 knots in those conditions.  You must be right about my 9 inch pitch offering less drag as I regularly hit 5 - 6 knots in those conditions.  Recently I sailed 90 miles in 14 hours, from Gladstone to Bundaberg, giving an average speed of 6.4 knots, though I had a perfect tidal gate, riding the ebb down Gladstone Harbour and the flood down the coast, so at least one knot of that was tidal flow.  I let the prop spin (engine in neutral), since research shows that offers the least amount of drag.  If you can work out an easy way to lift the motor and close the aperture, of course, you will have the best outcome. Good luck!  Anyway, it's more fun than mixing epoxy, is it not?  I have done enough of that to last a lifetime!
  • 27 Oct 2013 01:21
    Quote
    Reply # 1422029 on 1417956
    Deleted user
    Yes but your prop has 9" pitch vs ours with 6", more like a disk shaped sea anchor!
    I think the drag is worse in heavy winds (proportional to speed^squared), since the boat rarely got above 4.5knots on a broad reach in 25 knot wind.
  • 26 Oct 2013 22:49
    Quote
    Reply # 1421946 on 1417956
    Anonymous member
    I will be interested to hear if that makes a difference, Gary.  I have a fixed 3 blade, 14 x 9 inch prop that must also give a lot of drag.  I used to have an outboard that I could lift up and no prop aperture either.  The boat must have been faster in light airs but I am not sure.  Since I put the diesel in, I motor-sail a lot now in those conditions when coastal cruising.  If I ever got offshore again I will just carry a few more cans of baked beans!
<< First  < Prev   1   2   3   4   Next >  Last >> 
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software