Thread: GIS sail tweaking

Well, I've been sailing with the new boom. This week I am attending the Small Craft Skills Academy (Home Page) (Mackinaw City, MI session) with my Goat, Karen Ann.

We've had a wide range of conditions with winds running 12 to 25 mph with gusts to 30+ mph. I've sailed Karen Ann with full sail in winds up to 15-18; with single reef to 22 and double reef above about 22. (Yeah, I know, some of you guys are comfortable with different sail/wind combinations - I'm reporting what I was comfortable with this week.)

I'll say that each time I about reached the edge of my comfort zone, the boat became much more comfortable with the reef.

The new boom performed quite well without any noticeable bend in the conditions I sailed in this week. I am quite happy with the boom's design and construction method. I may experiment with different dimensions: thinner (lighter) walls, cross-sections and possibly some taper (again to reduce weight).

One observation from this Skills Academy is the confirmation that I am no where near the sailor I'd like to be. I'll work on that. I'd also add that, for those of us in the United States and Canada, if you are able to attend a SCSA session it will be worth your while.

Originally Posted by MiddleAgesMan

That sounds about right. I had figured about 30 pounds for a solid round douglas fir mast as per the original specs.

I was very pleased when my 3 inch tapered aluminum flagpole adaptation came in at about 19 pounds.

I'm not sure if you're interested in that data, MIK, but it is what it is.

Hi MAM,

That mast of yours was the final impetus to get rid of the round mast in the plan and replace with the square hollow one with the birdsmouth as an option.

The data about the Aluminium mast is already in the WIKI for the GIS rigs. Second entry actually!

WIKI for setting up and tuning Lug and Sprit Rigs | Michael Storer Wooden Boat Plans

MIK

Good news...

I've reduced the cross-section of my boom from 45mm x 60mm to 43mm x 58 mm.

Bad news:

Didn't measure the flex/stiffness of the "new" boom (too HOT right now and too many other things to do).

I'll take it sailing in a week or so and report on its performance.

(guess I can always check the flex/stiffness later)

Every step is a step forward! Another option about to be tested.

I'll add it to the WIKI when we have the properties and user experience to report!

MIK

Mik,

Please correct me if I am wrong...

Checking the WIKI, I realize the data for my Mk II hollow box boom isn't listed.

From another post: After I rounded-over the edges, shaped the ends a bit, drilled a hole at each end and sanded a bit, the new box boom weighs 2.1kg (4.62lbs). Vertical plane deflection (with 12kg suspended at mid-point) is still 7mm and horizontal plane deflection is still 12mm. This boom measured 45 x 60mm with 10mm sides. This is the boom I used last month at the Small Craft Skills Academy.

In the interest of putting off other projects, I pared this boom down from 45x60mm to 43x58mm. The result of running the boom through the thickness planer is that the sides are now 9mm.

So, we have the data for the MK II and partial data for the MK II.2. I'll weigh the MK II.2 boom and measure the deflection this week before I take the boat north for some sailing.

Confused? Me, too.

I've added it to the WIKI page.

Thanks BobWes!

WIKI for setting up and tuning Lug and Sprit Rigs | Michael Storer Wooden Boat Plans

I've added it to the WIKI page.

Thanks BobWes!

WIKI for setting up and tuning Lug and Sprit Rigs | Michael Storer Wooden Boat Plans

Originally Posted by Boatmik

I've added it to the WIKI page.

Thanks BobWes!

WIKI for setting up and tuning Lug and Sprit Rigs | Michael Storer Wooden Boat Plans

MIK, that link takes me to a page that hasn't been updated since 2010. Stuffed if I can find the data anywhere. I also wanted to check if I'd added my own Mk 2 stiff boom data. Wasn't it on Google docs somewhere as well?

You will likely remember sailing Hakuna Matata with the new Meranti stiffer boom? It still does bend a little when higher loads are applied by the kicker, but if I only use downhaul in the normal position, it is stiff.

Edit:
PS. Found it. Forgot that I had to first log in through my own Google Docs account to see the data. I confirm that my Mk 2 data is there.

Hi Bruce,

Have a second look at the Boom section ... because it is a embedded document the page it is embedded in doesn't get changed when the google doc is edited.

If it is the current version of the googledoc you should see BobWes boom version 2 fully filled in and 2a waiting for deflection and weight info.

If you don't see this you need to tell me and I need to work out a way of dealing with it!



MIK

Originally Posted by Boatmik

Hi Bruce,

Have a second look at the Boom section ... because it is a embedded document the page it is embedded in doesn't get changed when the google doc is edited.

If it is the current version of the googledoc you should see BobWes boom version 2 fully filled in and 2a waiting for deflection and weight info.

If you don't see this you need to tell me and I need to work out a way of dealing with it!



MIK

Hi Mik

It's fine, just me at fault. I didn't notice the second slide bar on the page

Okay, we've been polluting Clint's thread with all this talk of box booms when it probably belongs here anyway. So I'm shifting over.

Here's an evil thought. Someone stop me before I do anything too egregiously stupid....

In the interim before I get a box boom built, what would be wrong with testing a "stayed" boom? I'm thinking of running a piece of Spectra down the length of the boom, pulled as tight as I can by hand. I hook the downhaul to that, rather than to the boom itself. Then I make a spreader out of something stiff and locate it right at the downhaul. The line distributes the downward pull to the ends of the boom, so the stress on the boom is mostly along its axis. The spreader prevents it from bowing.

The danger, of course, is that the line will snap under tension and take out my eye. But, assuming I have given informed consent and all that, is it a viable experiment?

BTW, much, much earlier in this thread, we discussed a number of small tuning experiments, but we haven't posted any results except for spar deflections. Here are a few bits of feedback.

I moved my traveler back to the halfway point between bulkhead #4 and the transom. This completely eliminated the problem of the tiller getting hung up on it when tacking. All the way back at the transom, the leech doesn't tighten properly when sheeting in. That's okay at the midpoint. I keep it rigid tight. I moved the first block on the boom to the clew and usually take the sheet directly off the second block, rather than feeding it down to the block at bulkhead #3 and up again. I find this setup comfortable, snag-free, and responsive.

(I know I may be putting undue strain on the inwale at the traveler. There is no framing there to support it, as there is at bulkhead #4. But I haven't seen any damage yet.) (your suggestion of a screw through inwale into gunwale at that point is perfect - MIK)

I was getting a lot of weather helm, and countering it with the rudder was slowing me down. Shifting the halyard and downhaul so that there was a bit more sail in front of the mast fixed that. I've got a full 16" there, with the luff just about parallel with the mast. The helm is so well balanced that I hold the tiller directly on the centerline of the boat on most points of sail. There is a noticeable increase in speed.

Following Joost's lead, I got rid of the square lashing holding the boom to the mast. I re-tied it from the front of the boom to a loose loop around the mast. It's purpose is just to prevent the boom from sliding forward when I raise the sail. The downhaul holds the boom close enough to the mast so the lashing is unnecessary. No more tangles with the cleat when raising and lowering the sail and no more jamming of boom against mast.

Adding a stylish black banner at the tip of the yard does nothing for the boat's performance, but it sure looks good!

Holy beep, Paulie, everything you have just described, is the way I changed my rigging as well.
(1) no more square lashing, I use the loop around the mast to the forward boom end like you.
(2) I've tried different amounts of sail forward of the mast and settled on the 16 inch spot as providing the most balanced helm. I too moved both yard lashing and boom retainer to balance this out.
(3) My traveller is where yours is, about 16" off the outside edge of the transom and I like it there, but I still bring it down to ratchet block at the midseat rope saddle. I switched to a big though light Ronstan series 55 ratchet block for the sheet. It grips well and makes very cool ratchety sounds.
(4) I ran my outhaul under the boom to a boom lashed block about 1.5 feet aft of the mast using some leftover spyderline, then down to a 3 to 1 terminated with a Ronstan RF45131 series 40 block with cleat on the deck just aft of the mast. With this arrangment I can tweak the downhaul pressure (no choice actually!) almost like a boom vang/kicker. Another aspect is that it pulls the aft end of the boom towards the bow. This opposes the forward boom lashing, and the effect is that the boom stays very snuggly against the mast without a square lashing.

My hope as well was that this would act as a stay to the boom to help prevent bending, but in reality it only increases the bend. O. The only solution to the bend issue is I think a new stiffer boom, and I am reading the ongoing discussion here and on facebook with great interest! I did stop by Home Depot about five times to wander the wood, and see what might be of use, and came upon a stock of already machined high grade Douglas Fir "rail cap" in lengths of over 12 feet. It is heavier, and very stiff, and I am tempted to bring one home and give it the stiffness test, measuring my stock 40mm sitka spruce in comparison. Not as sexy as a hollow box, but it would be fun to weigh it and bend it for data, and you never know, it could work well.

I really like having a light boom. It's responsive, and you can point it up at the sky sailing by the lee in light airs without breaking out an oar for a makeshift whisker pole. It would be cool to have a boom twice as stiff, but not any heavier!

Pointing - I'm still not quite happy with my pointing ability, but it's better! I can only judge against the marconi rigged sloops and a few racing dinghys where I sail. It is very much fun out in the ocean pacing 30 and 40 footers in different points of sail, and you're the only one out there in a small boat! A constant that I have noticed is pretty standard - for a change in apparent wind direction, the Goat prefers a course correction rather than a sail adjustment.

Wind Indicator - I added a mast head wind indicator (modified Davis "spar fly"), and I use it constantly in conjunction with two sets of tell tales.

Sail - My Duckworks sail is stretching out I think - which is a good thing. I am using it unlashed without battens, and I give it a fairly loose outhaul sometimes if I want more depth in chop. It does help, (thanks Mik!) I am still really curious about the shape and attack angle of the leading two feet of the sail when it is on the leeward side of the mast (no mast wrap), as I think this has everything to do with how well the boat points on that tack. The only adjustment I have to try to tweak that is the choice to lash or not lash the foot, and the amount of outhaul pressure. I can't wrap in my head how adding downhaul pressure will change much of the sail shape other than the tension in the luff. I can make the boat perform well pointing with the sail on the lee, but I have to give up some degrees of pointing compared to the mast wrapped tack!

Hi Paulie and warmbeer

The loop around the mast to the front of the boom is, I think, a good idea. I have not tried removing the square lashing so will have to give that a go.

Now that you have this restraint on the boom, have either of you tried moving the downhaul any further aft to increase the vanging effect?

I am a little worried about sheeting from a traveler between BH4 and the transom due to the lack of support there. Perhaps a big screw or 1/4" bolt epoxied through the inwale and gunwale to strengthen it, but the boat is very strong and probably doesn't need it. (I have tipped mine over on the beach while fully loaded with water to empty it and there hasn't been so much as a groan from the hull). As I carry my traveler drum tight, I will leave mine at the transom. On a beat, I'm hauling my boom further aft to create weather helm (otherwise I have lee helm), so the sheeting from the transom works well for me. Certainly I have no issues with generating enough leech tension. By the way, I carry two 55mm ratchet blocks, one on the traveler and the other on the mid seat. Both can be turned on and off. As I've changed my mainsheet to 6mm polilite, this makes it more comfortable to manage when the wind gets up. This lightweight sheet is great in the light stuff as it runs so freely and helps keep the boom out and the sheet out of the water.

Paulie, I think your stayed boom will be great for hooking up around body parts and PFDs. Worth a go though for fun. Rest assured, you can make a very light and stiff boom. Don't be tempted to use heavier timber to achieve the stiffness. Use the lightest timber you can as it's all in the dimensions. I managed to find some super light meranti for mine, so that it's stiff but still light. Still taper it at the front and back to make it look nice. Has anyone made an I-Beam boom?

As for pointing ability, the most important thing here is leech tension and boom position. You will need to have the back of your boom pointing at the transom corner, and to do this you need a tight traveler to keep the boom there when you crank on that last bit of mainsheet that puts in the leech tension. The aim is to have the leech straight like a blade. Naturally, the board has to be all the way down and of course, you need a drum tight luff as well, so plenty of downhaul is needed. I've found that having the automatic Ronstan series 55 ratchet on at the traveler helps because you can tension the leech with the mainsheet to where you want it and then just let some of the sheet tension go. This takes some pressure off the middle of the boom while the S55 at the traveler end holds the leech tight. Vital also to pointing is fore/aft weight distribution which needs to be centred as close to the centreboard as possible while keeping the boat flat to generate the maximum lift. Do this and there's no reason for you not to be pointing at 80 degrees, which is close to matching those Lasers and excellent for this rig. Over time I've become quite amazed at the potential of the lug rig.