Thread: GIS X or Raid Special

Originally Posted by Boatmik

Howdy,

Good discussion.

The most obvious way for most people to deal with adjusting the stability is to reef the sail. So this discussion is in the context of trying to increase the capability of the boat.

There is no problem trying the centreboard. I'd prefer it of course if the boat has a regular centreboard as well!

One problem can be, of course, that the board can be a real cow to get out of the case and may not be able to pull up the board far enough to pull up on the beach without interfering with the boom. I think you would end up dropping the sail and paddling, rowing or drifting into shore. A good handle on top of the centreboard and a hole/s to put a pin through to hold it at different heights.

The final thing is at low angles of heel a heavy centreboard makes very little difference, and comes into play as the heel increases.

A big advantage might be after capsize.

It would be interesting to see what the difference is.

Hi Mik, yes, thanks for these thoughts. I am building the standard centreboard, will see how I go with that, with and without some sandbag ballast for when I'm on my own in the boat. May try to make a lead weighted board next winter just to see what the difference is. Short term interest is to have the boat docile enough to go out on my own with three kids and know we won't get into trouble, medium term interest is being able to push the limits of dinghy cruising, again without getting into trouble.

As you say, there are some downsides and hassles with raising and lowering a heavy centreboard but I figure if you're going to have some ballast it might as well be where it can do the most good so you don't need so much of it.

Ian

Howdy,

Good, I am all for the experiment.

The ballast in the bottom of the centreboard is not necessarily the best place because you can't put much there without it becoming inconvenient. The sandbag solution might be more effective because you have have serious weight.

That's what David Graybeal did for the first year with his boat as he got used to it. He doesn't use the bags now.

Thing is, like you say, try different things and make a rational decision about what the results are.

MIK

I could have done with some live ballast today! In the absence of some live ballast, I think some sandbags would have helped because I was so overpowered on the beats. The reaches and runs were great though, just the beats. Boy, I'm going to be so stiff and sore tomorrow!

Ian, I saw today the hassles that a ballasted dagger board gives in some Access dinghies at the dam today. It takes two people to remove it, one to hold the boat steady while the other straddles the casing and heaves. It wasn't a simple operation at all. The DBs are not that heavy (20kg I would guess) but they are not that easy to manage. I can see you getting into a situation where you need to raise the board, but you won't be able to because of the pressure and the weight. Sand ballast is the way to go I think.

The other consideration is that you may need some strengthening of the casing also.

Originally Posted by woodeneye

Ian, I saw today the hassles that a ballasted dagger board gives in some Access dinghies at the dam today. It takes two people to remove it, one to hold the boat steady while the other straddles the casing and heaves. It wasn't a simple operation at all. The DBs are not that heavy (20kg I would guess) but they are not that easy to manage. I can see you getting into a situation where you need to raise the board, but you won't be able to because of the pressure and the weight. Sand ballast is the way to go I think.

The other consideration is that you may need some strengthening of the casing also.

Thanks for the observations on some hassles with a balasted daggerboard. Yes, it might be more trouble than it's worth, but it would be interesting to see what difference it can make to ultimate stability versus weight in sandbags in the boat.

Maybe Mik can comment, but I would think the centreboard case is strong enough as is - forces from normal sailing loads and hanging an 80kg + body off the centreboard to right the boat after a capsize will be biggger than the effect of perhaps 15 - 20 kg weight in the bottom of the board.

Ian

Balasted daggerboard?
It is a popular solution for few kinds of small cabin boats in my country (example as an attachement), but it is no invented here. The idea is really old:

You may be right, the casing structure is very strong. A couple of us (Callsign and me that I know of) have hit bottom at speed with no ill effects to the boat (I broke a thumb in my incident, so the crew is the more fragile component!).

The other contributing factor to stability in the Access dingies is that the crew sit on the floor, so they are the ballast as well. If they ship water due to heeling too far, the water is concentrated near the middle due to the shape of the side tanks, so this only adds to stability.

Callsign has also used sand ballast in the early days following his launch, so he might comment as to the effectiveness of it, but I seem to recall that it helped him a lot. I think I will make up some sand filled sausages and just leave them in the shed at the dam to use in heavy conditions like we had yesterday.

I used 100 lbs on ballast in the beginning on blowing days early in my summer as I got used to the Goat. Two 50lb bags of sandbox sand from the hardware store double bagged in nylon shopping bags and then tied together through the bulkhead to keep them from sliding around.

I was having issues keeping the boat from capsizing due to several different factors. These included:

-An initial bad rigging job with the lug rig, which was quickly fixed-- (still having some issues with sail tension and wrinkles, but this did not contribute to the capsizing).

-Not reefing and sailing with all 105 sq.ft. of sail up and out when I was solo with no hiking straps in mountain lakes with gusty unpredictable winds.

-Being too far forward to adjust something, which takes the stern out of the water. The boat is then balancing on her fine entry bow, and if one is not careful she'll go over on top of you, especially in heavier seas, but when calm too.

-Stepping out of the boat with the sail up to either grab a forgotten item on the beach or dive to get a tangled anchor. Obviously, a numbskull move.

Once I lost the hubris and reefed when I thought appropriate for me, watched my weight and physical position when solo and forward, and dropped the sail when exiting the craft at all times no matter how calm, I stopped using the ballast.

I have never capsized with this modicum amount of ballast in the boat. It also made crawling back into her after a swim a little easier too, and she rides at anchor more gently. Camping gear, food, and water supply could be your ballast too.

Now that I don't use the ballast and I apply the lessons learned, I barely capsize (I still like to push it sometimes).

The boat's stability increases dramatically as weight is added.

Thanks, callsign for such great info. (And for going so hard out all summer to find out so much, and for reporting all the experience you've had, even the potentially embarrassing bits.)

My building continues, bogged down a bit by getting sidetracked and doing fancy little bits, but should be past that soon and onto something that looks like a boat. Pictures and details soon.

Ian

I agree, all the sailors who have been putting reports in here have provided a huge backbone of information.

I've moved more to the pseudo wiki on my website.
http://www.storerboatplans.com/wp/de...r-google-docs/

If anyone want to be able to add more to the wiki from these forums or emails I can send them permission to edit the document online!

One area we are missing out on is in finished hullweights for different materials for the Goat. I have Peter Hyndman's original build (127lbs) and Woodeneye's amazing paulownia framed 105pounder, but I need more. So if anyone else has a weight on the tip of their tongues they can add it or just mention it here with the list of timber species and if any glassing was done and I will transfer.

It is going to be a seriously useful document.

Best wishes
Michael

This has been an incredibly interesting thread. From what I've read, I am thinking that Mik hasn't put up a stretched GIS design yet (17.5 - 18') because it would depart from the cartop capability and efficiency of the Goat, and would not be a unique contribution to designs at that length (ie., not as marketable). I still like the idea of a longer GIS, with a bit more seating comfort for hiking, room for four when daysailing, and faster rowing with more waterline and two rowing stations. There are a number of such designs available for Raids, but none as light or as fast under sail as I imagine this GIS X would be.

Originally Posted by JJMc

This has been an incredibly interesting thread. From what I've read, I am thinking that Mik hasn't put up a stretched GIS design yet (17.5 - 18') because it would depart from the cartop capability and efficiency of the Goat, and would not be a unique contribution to designs at that length (ie., not as marketable). I still like the idea of a longer GIS, with a bit more seating comfort for hiking, room for four when daysailing, and faster rowing with more waterline and two rowing stations. There are a number of such designs available for Raids, but none as light or as fast under sail as I imagine this GIS X would be.

Maybe Mik hasn't drawn a bigger goat as the existing length is already optimal. It's easy to see the weight nearly double by going up in size by only about 20%. Even with all Mik's magic, it would push the weight out of the 'easily picked up at either end' range. 20% longer wouldn't add much speed - what you gained in lower wave making resistance would be lost in greater friction resistance from more surface area and weight. (Though you'd perhaps be able to carry a little more sail). I can see some good points to the yawl, but I think a standard GIS would beat a yawl rig, especially to windward, even if it was 2 ft longer.

I think the gains people want (speed for raiding and seaworthiness for expeditioning) can almost all be achieved within the current hull:

Speed Gains For Raiding:

Keep the boat as light as possible.

Continue to work on sail/rig development. Bermuda rigs have more than a hundred years of racing development, a few more development cycles with the lug should see some gains in lift to drag to help performance to windward. Remember Joost was keeping up with much bigger boats with good crews on Loch Ness, with a sail/rig combination that probably had some room for improvement.

Match your crew to the likely conditions: If anticipating strong winds, borrow a girl from the rowing club - single scullers are good - at least 6ft tall with long legs, big shoulders and weighing more that 180 pounds (while maintaining agility) is ideal. If winds will be light, take out someone more petit.

Two person rowing - should be possible to set up the existing GIS for two person rowing, perhaps with a 'ladder' that fits down the middle with two sliding rowing seats on it. (Make it movable so it doubles as a hiking plank for beating/reaching!?) I suspect 2 feet more length would add drag/detract from speed while rowing if you ran it through a drag prediction program.

Increasing seaworthiness for expeditioning:

Put in a carbon mast - big gains in stability from reduced weight aloft. Also the ability to step and unstep the mast on the water as it's so light. Expensive, but cheaper than building another boat.

Widen/box in the central seat to add storage and extra buoyancy. Should be possible to add 200 litres of buoyancy/gear storage, all in exactly the right place for stability.

Add some extra buoyancy wherever you can - I'm thinking about some open cell foam (mattress foam) covered in waterproof PVC and tied down to the floor in the forward area, and either side of the area behind the middle seat so any water in the boat stays in the middle and adds/not detracts from stability. Some more up high so the boat will always float high, level and stable with the crew in it if swamped.

Add some drainage tubes as Watermaat did. I don't think he tested them in anger, but I'm going to put some in, however more towards the corners of the transom as Keyhavenpotter suggested. I think it's possible to get a boat without a double floor to almost self drain - my idea is that with the drainage tubes in the right place and angle, and some foam buoyancy on the floor along each side, all but a cup or two of water will drain out if the boat is at about 30 degrees of heel. I'll have a better idea of how to place both buoyancy and drainage tubes and if the idea will work once I have the hull in 3D in front of me.

Add a PVC foredeck and inflated breakwater to minimise the amount of green water coming over the bow when you're going fast in the rough.

Make the gunwales wider both on the outside and with wider inwale spacers in the inside so it's a more comfortable seat. Wider on the outside will also help knock down spray and shouldn't add any weight if you make them of lightweight timber with only a thin cap of hardwood on the outside.

The big plus of not increasing the size of the boat or adding structure is you maintain the ability to carry it up a beach - I'd rather ride out a storm on an expedition sitting on a log above the beach with a fire in front of me and the boat and tent on the other side of the log, all well above the high tide line.

As I think Bolger said, big enough to blue water cruise and live on board or small/light enough to fit on a roof rack.

Ian



Will edit more in soon - have to sort dinner for kids!

Ian

Good ideas Ian. keep em coming!

Howdy,

I was thinking of getting two rowing positions by adding a drop in longitudinal seat along the top of the centrecase and extending back a foot behind the mid seat. That would allow for two rowing positions.

But also remember Joost came third against all the multioared boats in the Caledonia Raid.

I don't know how much of that is a measure of Joost, how much the Goat and how much keeping things light and simple.

MIK

Originally Posted by Boatmik

Howdy,

I was thinking of getting two rowing positions by adding a drop in longitudinal seat along the top of the centrecase and extending back a foot behind the mid seat. That would allow for two rowing positions.
MIK

Yes, very much how I was thinking - a single plank or ladder arrangement that fits lengthways and provides one seat over the (front of?) the centreboard, another behind the existing middle seat. Good to incorporate it with a short daggerboard to help with tracking without adding too much wetted surface area. All in a way that can be stowed out of the way when sailing. (Or I keep having mad ideas of using it as a leaning plank when going to windward/reaching!?)

Ian