Rob's Racing Harrigami Report 1 2

Rob: 'I was smiling with Harrigami on the trailer yesterday, but today not so good. Rudders need a bit of a rethink. Spent all my time looking at them, didn't really notice how it floats. Doesn't take much to move it though. Will do some drag tests once I sort the rudders.

I will write the full story when it either works, or I run out of ideas. The latter has never happened, so I figure it will work eventually.'

Click on the images to enlarge.

News from the great big test tank

29th March
Did some tow tests today. Not very satisfactory as the water was chopped up by all the fizz boats going out for the day and there was only one person in the tow boat so my boat was frequently in his prop wash or the tow line was at an angle. Therefore, I think we can assume the following are on the high side.

Drag figures are tow speed of 6.5->7 knts = 16 ->20 kgs, 9->9.5 knts = 28->32kgs, when trying to get to 12 knts it was around the low 40's but would bang on the end of the spring so I slowed so that we didn't damage the scale.

Speed was measured by gps, drag by a fishermans scale on the tow line. Not as accurate as the gps, but well within the scope of the min and max numbers.

These numbers are marginally less than the numbers in Design for Fast Sailing (Frank Bethwaite) for a 14' (4.3m) 238 kg/525 lb performance planing dinghy in flkat water. I was solo, but did have anchor, warp, outboard and fuel on board. All up weight probably 600 kgs/1,320 lbs. I have no idea how these relate to other multis, but they look pretty impressive to me.

We did not get the opportunity to test weight movements, nor the effect of the rudders, which is a pity, but for this sort of accuracy, it is a three person job, much earlier in the morning than we managed. Unfortunately no pictures, but the wake from the hulls is minimal. Less disturbance than the old hulls, which is gratifying, though not really surprising.

Can't say the same about the rudders which are still not right, although the steering system itself now works. I need to lengthen the tillers (400mm was never going to be enough, but I wanted a feel for the loads with various amounts of rake), and maybe play with the leading edge shapes a bit. It is fascinating to be able to watch the flow as the rudder is turned.

The outboard bracket being as far to windward as possible (for racing weight reasons) did not help the rudders, but as it is only for getting in and out of marinas, I can live with this. Having a crew to steer the front rudder would help here as well. The bracket itself also needs some work. It is an interesting task supporting a tilting bracket on a 200mm/ 8" deep beam. The 15 hp outboard is way bigger than required and is for sale/swap for a smaller one. Did not do much more than idle most of the time. Did get 8.5 knots at not many revs at one stage, before the stretch in the rope supporting the bracket got out of hand.

So, still plenty to do, and I am not yet convinced that the rudders will be any better than the old ones. The sails will be ready this week, (jib was a bit long on the luff) so should have some sailing news next wekend.

Regards, Rob