Thread: GIS handling characteristics

Mik, I just pulled my Duckworks sail off and laid it on the floor with a straight edge (my boom-- very straight) and the foot of the sail is cut straight across, there is no curve between the tack and clew along the foot.

MIK's sail plan (the drawing with sail dimensions and notes for the sail maker) clearly states that some amount of bend in the boom will take place--2 inches plus or minus IIRC. Apparently the sail maker DW uses didn't bother to read that note...or (what's even worse) didn't consider it important.

Howdy Callsign,

Thanks for doing the measuring. I pre-empted this might be the case and mentioned it to Chuck during a skype talk we had yesterday about the Quick Canoe France trip.

He was emphatic ... if there is a problem they will fix it up ... so can you send him an email. At this time of year it might take some time to sort out because generally sailmakers are flatstrap at this time of the season (in the US). So might be best for you to keep using the current sail until the weather gets more dodgy for sailing.

I think it is most likely that the sailmaker drew the line straight before lunch and then had to pull the sail up off the floor and when getting back to it forgot that the round hadn't been added yet. Something like that.

So drop Chuck a line and he will work out the best solution with you. When there have been probs in the past (the very few times it has happened) Duckworks has just been magnificent. They really do back their stuff.

Best wishes
Michael

Today I'm finally beginning to see the light behind this boat! Thank Poseidon!

An epic day, solo, 100 lbs ballast, solid southern winds up to 20mph-- full sail, no reef, I wanted to see how the new loose foot would behave. I still need to drill a new hole to fix the head/throat per keyhavenpotter, but I had the lashing at the throat very tight and only a little tension from the luff creeped into the head. This will be completely fixed soon, but I want to throw another layer of FB tape where I'm going to drill and didn't have the time.

With the loose foot (as opposed to wrinkle-foot) I gained, no sh*t, at least 10 deg. if not more of pointing ability, in addition to speed. I thought this boat pointed like a pig, like a Beetle-Cat, and today's sail improvements proved that wrong. Thanks to Poseidon again!

During lunch I improvised a hiking strap and for much of the time sailed I am Zinea, Pterodactylus like my old Laser, with nothing above the knees in the boat, body straight out like a board, hauling on the sheet, boat slightly healed cleaving the chop as I outstretched my hand to skim the top of the water as we flew along. I'm glad I still have my Laser hiking pants.

At one point I fell out backwards when I missed my improvised hiking strap, my foot got hooked around the mainsheet and I got dragged for a bit while the boat kept going since the sail wouldn't let out, but that's all part of the fun.

She jibes quick and tight too, I was orbiting the dock waiting for a space to come back in and pulling 360's close to shore with shocking precision. It was nice.

Ran into (figuratively) a Core Sound 17 and a had a good jibber jabber with her skipper. It was nice to see another homebuilt boat and do the comparison thing.

I'll have some pics on the blog up later, maybe tomorrow, but I must run to dinner now.

She's starting to fly, finally! Finally!

Need oars so I can do some Maine Island Trail!

Another thing I realized today was that this boat can be sailed very physically, or more placidly with its myriad of reefing options.

I like the 3 reef point idea for this flexibility. Like today, I wanted exercise, and I got it, and I was still fast. One reef tucked in would have been appropriate (and maybe faster), but today I wanted some exercise and excitement and push her, and I got it in spade. My abs are gonna get the girls if I keep it up! (don't tell my wife).

Sorry for the third post, but I'm whooped--

Mik, I moved the traveler back one inwale space, and tied the aft block as a clew tie-down for the mainsail. You said this would help reduce bend correct? It seemed to work quite fine.

I wish I could have gotten a picture of the loose-foot under load, but it was more leg-o-mutton than Laser loose-foot, if you get my idea. Again, maybe I should go through the spar discussion again, but with compression forces, I'm thinking of building up a stiffer spar-- mine now is stiff vertically, but laterally not as much. But, I could see how that hollow foot helped with power through the chop.

I am definitely looking forward to halting all luff tension from reaching the head so I can release some pressure up there too.

Finally, thank you all again for the international effort at getting my boat running right, I appreciate it, and if you could have seen the smile on my face today you would've felt good about your brainstorms and efforts!

During my rowing trip I realized how must easier I could walk around the boat without the mast. I could stand on the rear deck and raise and lower the rudder and go all the way forward to my front locker.(front air chamber) without the boat tipping. I began to wonder how much just the mast contributes to righting (maybe unrighting in the case of my capsize) moment of the boat. It's a very tall mast for a light boat. It would be interesting to see what our masts weigh and where the balance point is on each mast. A heavy mast with a high center of gravity will tip faster than one with a lower center of gravity.yet weighs the same.

So how can we measure our masts and compare apples to apples?

Originally Posted by john goodman

During my rowing trip I realized how must easier I could walk around the boat without the mast. I could stand on the rear deck and raise and lower the rudder and go all the way forward to my front locker.(front air chamber) without the boat tipping. I began to wonder how much just the mast contributes to righting (maybe unrighting in the case of my capsize) moment of the boat. It's a very tall mast for a light boat. It would be interesting to see what our masts weigh and where the balance point is on each mast. A heavy mast with a high center of gravity will tip faster than one with a lower center of gravity.yet weighs the same.

So how can we measure our masts and compare apples to apples?

Hi John, easy:

(1) Measure total weight of the mast.

(2) Put the mast on the ground and put a stick under it near the mid point. Move the stick down towards the base till you find the balance point.

(3) Measure the distance of the balance point from the mast base.

Be interesting to see what it is, compare values. It would be possible to put the above numbers into a stability program and see how much stability improves with a decrease in mast weight, decrease in weight aloft, but basically it's as you would expect - reducing weight in the mast is good, the higher up the weight is removed the more positive effect that weight reduction has.

Ian

Great sailing stories! That is my feeling about the Goat too. It sort of has multiple personalities. Or maybe it is me.

John's point about the mast is right. The original solid round mast like on Peter's "Gruff" (the planing videos etc) takes such a lift to get into place so I finally succumbed and did the rectangular hollow mast at about half the weight.

The birdsmouth is pretty similar in weight to the hollow square I believe.

IT was also in the back of my mind that the lighter mast would increase the stability as well.

MIK

There was a problem today with the manning of the rescue boat on the nearby lake where we were to sail today, so unfortunately, sailing was cancelled. Because the lake is owned by the water authority, they call the shots, so the rules are, no available rescue boat, no sailing. It would have been the first sailing experience for my eldest daughter (22), however she was upbeat because she learned all the parts of the boat and how to rig it.

We took the opportunity to make some mods that Keyhavenpotter has enumerated in previous posts. The first thing I corrected was the throat lashing at the front of the yard, which was not tight enough. Then I slackened off the peak so that there was at least 2.5cm (1") of slack between the peak and the throat. What a difference that made! The leech was falling off a bit when the downhaul was cranked in hard, and suddenly this was pretty much fixed. Good tip there mate .

However, while I now had some good sail shape, I was still not completely happy with the leech, which had some remaining slop. There was a good 10-15km/h breeze, so I also took time to fiddle with the leech line, to see what effect it had. I was amazed. I had thought that tensioning the line would tend to "close" the leach, but it doesn't all all. What it does do is get rid of any flutter and helps to achieve a nice even leech curve. Guys, if you have the option available, definitely get a leech line installed!

I must have spent a good 2 hrs fiddling with the boat on its launching trailer, and it was time well spent, because the sail was looking pretty good by the time we packed up.

One other thing that became apparent from today's analysis is the need for a kicker. I did jury-rig a kicker and there was a remarkable difference in the results I was seeing on the shore while moving the boat around on the trailer to look at the effect it was having from different points of the wind. The downhaul alone is definitely nowhere near enough to properly control the leech because it is really too far forward on the boom to have much effect.

So sadly, there was no sailing, but I still learned a heck of a lot about my balanced lug rig. Maybe some pics of the sail in action next week

Originally Posted by Boatmik

Great sailing stories! That is my feeling about the Goat too. It sort of has multiple personalities. Or maybe it is me.

John's point about the mast is right. The original solid round mast like on Peter's "Gruff" (the planing videos etc) takes such a lift to get into place so I finally succumbed and did the rectangular hollow mast at about half the weight.

The birdsmouth is pretty similar in weight to the hollow square I believe.

IT was also in the back of my mind that the lighter mast would increase the stability as well.

MIK

Having rigged my GIS with it's hollow square mast a few times Mick, I must say it's dead easy due to it's light weight. I have some arthritus in my elbows and shoulder, but I can stick the mast in on my own without any trouble at all. (It's something that bothered my thoughts a bit while i was building) A number of people have remarked on seeing the square mast and have been blown away by it's light weight compared to their aluminium ones. I've even told a few it's hollow, hehe.

I'm thinking that with a sealed hollow mast and boom, it's unlikely that the GIS would turn turtle when capsized. Seeing as it doesn't float that high either when capsized, it seems pretty unlikely that it would. Has anyone gone completely turtle with their GIS?

My tapered spun aluminum flagpole mast weighs 20 pounds give or take a couple ounces. Its balance point is, surprisingly, about an inch below center. The spinning process used to create the taper results in a thicker wall at the 1 7/8 inch thick top than at the 3 inch bottom.

It's sealed and floats very well. Combined with the flotation provided by the Oregon yard there doesn't seem to be any chance of the boat turning turtle.

Originally Posted by john goodman

I began to wonder how much just the mast contributes to righting (maybe unrighting in the case of my capsize) moment of the boat. It's a very tall mast for a light boat. It would be interesting to see what our masts weigh and where the balance point is on each mast. A heavy mast with a high center of gravity will tip faster than one with a lower center of gravity.yet weighs the same.

Three possible ways to reduce the weight of the mast further:

(1) Make the inside taper on the hollow wooden mast a little less as you get up high and then take some thickness out of the walls up there once it is glued up so the outside diameter stays the same as before but wall thickness is less up there. Could be tricky to do accurately, and I'm not sure how much weight it would save. I think Mik has done this sort of wall reduction trick on a birdsmouth mast somewhere.

(2) Take a 0.5mm kerf japanese saw to an existing mast, rip it in half lengthways by hand then reduce the wall thickness of the upper part from the inside using 40 grit sandpaper wrapped around a former, then glue it up again. Only for the brave! (I've no idea if this would work.)

(3) Go Carbon - I'm not far away from ordering a carbon mast and yard for my Goat (under construction). Weight about a third of hollow wooden so maybe 9kg in total saved from aloft. About NZ$1000 more than going wooden but 40-60 hours less on spar construction. I've been a bit nervous on the yard situation - section size, wall thickness, amount of taper..., but I've had some good feedback from keyhavenpotter and the sparmaker, think I have it all figured out now. Even with the hollow wooden mast, the weight aloft is 20% of the all up weight of the boat, so it will be interesting how much difference subtracting 8 or 9kg from that weight will make. My guess is that it will be worth almost as much as another (lightish) person sitting on the high side as the boat heels.

Ian

It will make quite a lot of difference.

MIK