Small Tri Test Platform

[Gary Baigent]

Using the main hull's dagger to counter the leeway isn't always the best solution. It will give you a big increase in wetted area & that's usually very slow.

If the angled lee foil has enough dihedral (45 degrees or more), there will be a larger projected area for resisting leeway than for providing vertical lift. In a lot of conditions, the sideforce is smaller than the vertical lift, so if the boat can fly OK, then it should be able to resist the leeway too.

The times that I've use the daggerboard, in addition to the foils, on Broomstick the boat's performance was seriously degraded. Also, I'm much happier with the boat since I cut the vertical fins off the bottoms of the V foils.

Because I sail Broomstick on a small lake with few other boats around, there are no good yardsticks for comparison, so I have no objective data to back me up (other than top speeds recorded on reaches). But my subjective feelings are in agreement with my objective arguments in this regard.

Hi Doug, (the other), It's interesting how we all go our different ways. When I first launched Sid (and also Groucho in the early days) I thought the deep foils would be sufficent to gain okay windward performance ... but I was very wrong. The windward foil, because of it's depth, just dragged along and the leeward angled foil felt like the boat was slipping sideways (we sail in waves and reasonable strong currents here) but since fitting a high aspect ratio main hull dagger to Sid, (also Groucho way back then) beating to windward improved dramatically.

 

[Doug Halsey]

Hi Gary : I was referring to V or angled foils with significant dihedral, which retain useful lateral area when flying. If the foils are more akin to T's or J's, then what I wrote would obviously not apply.

Since the foil in this thread has a nearly horizontal segment at the bottom, which becomes a larger proportion of the total as the boat rises, then you are certainly correct. Adding a daggerboard would probably help. However, I expect it would be slower than having a different foil configuration where this wasn't necessary.

Paul : Rather than a full-sized daggerboard, what would you think about adding a vertical fin to the foil ? (You can call it a Z-foil, if you must.)

 

[P Flados]

Doug H (hard to believe we have too many Dougs for easy conversation)

A big part of the whole concept is the ability to sail in coastal inland waterways. These waters have lots and lots of shallows and sandbars.

Everything on this boat is "kick up". The rudder T foil is actually showing some wear & tear from regular use of the this feature. This adds some extra complexity, but it also adds options.

For the ama foils, a turn down on the ends adds more area (drag) for all sailing modes. It also makes ama foil kick up events more frequent. Oh, and one other thing, it is quite a bit of work.

The leeboard experiment will actually be very easy. If it works, a permanent add on is also very easy. Since all of the foils can be rotated up out of action, the only real performance cost for times when it is up is the small additional weight. If I want to get fancy, I can even implement a lee foil with a nice asymmetric foil and either side swappable or one on each side. It will be lightly loaded. As such it can be a straight carved softwood 1 x 6 or 1 x 8 with nothing but paint on wood for finish.

 

[Doug Lord]

Test Platform

Paul, since you're going to try a daggerboard* anyway, you should put a lifting foil on the bottom of it and give it a try. You could manually pivot it to change AOI and I bet you'd fly right off the bat.......Design
*the leeboard could be made to work

 

[P Flados]

The only reason for the leeboard is when working to windward in tight quarters.

This requires absolute minimum drag. Also when not beating, I need to get the board out of the water and not be in the way of anything. No tee foil for the leeboard.

Unless I can get foiling speeds upwind (I am not optimistic), I am pretty sure the wide chord straight board really is best for upwind.

For a long term optimum upwind configuration, this boat could easily accommodate the ability to swing the Tee rudder up out of the water and swing down a wide chord straight rudder.

I would love to try a fully contained Tee foil with flap and wand similar to Osprey. With it mounted in the middle similar to your RC boat, I might get low speed full foiling ability. However, it would be a lot of work and I do not see how to engineer in a "kick up" feature that could handle regular sand bar impact. Still it would be fun and it would be interesting to see what kind of performance would result.

For assured full foiling, new ama foils are probably needed. I have been toying with the idea of building a pair of J boards with either active control full pivot (trifoiler style) or wand controlled flaps (I know it is possible, I keep waiting for someone to do it).

 

[Doug Lord]

Foils

Paul, have you seen this? Done by Magnus Clarke......

 

[P Flados]

Yes, I recall seeing his sketch.

My concept is much more of a J with a substantial straight horizontal section.

Flap operation with a "flex drive cable" would be about the best option I can think of. Problem is that I do not know of a source for a Stainless Steel version of the right size / rating.

I would also think that something approaching an elliptical planform for the horizontal section with a variable width flap would be better.

 

[P Flados]

It was in the 60s and sunny yesterday. Loaded up and went Wrightsville Beach - Banks channel

Forecast was 8 kts wind, so I took the larger sail.

Wind was 12 to 15 kts straight up the channel

It quickly turned into one of those crash and burn days

I lost it on the first run away from shore. Before I ever got up to any real speed the sail went from near no load to hooked up from a gust.
The lee ama went way under quick. I steered up for no effect (the drag from the submerged ama probably turned me more down instead) where I should have uncleated the main sheet fast

I have had this boat on its side more than a few times. The only other time out with the big sail I had done about the same thing. However, that time I was in the pond with no current, no chop and warmer water.

I went over the high side and quickly got it up back upright and climbed back in without getting my chest wet.

I was happy at being back upright and dry until I sized up my situation

Normally I would have got the boat upright, stayed off to the side and bailed the cockpit to around 50% before climbing back in. The boat forward section is sealed (kind of) and I have foam and other flotation stuffed in the rear section. With me not in the boat, the boat has about 4" of freeboard just after being begin pulled back upright.

With me in the boat, the front was just above surface, the rear was just under. There was no way to bail out back to normal without jumping into the water. I should have, but I was worried that the water was too cold (lows have been mostly in the 30s - 40s in the previous week). I was also worried about the big sail, the strong wind, the nasty chop and the current.

I could not really turn back but was able to start making slow headway to the beach area just across the channel.

About 3/4 of the way across, a motor boat offered me a tow. He threw a life ring on a rope in front and to the side of me and then start to circle around me to drag the ring to where I could get it.

The ring snagged the front of the boat while he circled behind me. He just kept going with out watching or listening (I was yelling) and drug the boat backward until the bow went straight down and the boat was floating with the mast and cross beam sitting on the surface. It then went over to one side while he continued to circle. Not good for my wimpy little boat

I got him to stop. I untangled the life ring from the rigging. I swam with the ring around to where I could hold the ring with one hand and hold the boat with the other. I directed him to carefully circle the correct direction and slowly head over to the beach. Yes I was getting chilled and it took a lot of determination to hold on.

We went about 50 yards with the boat on its side and the mast / sail to the rear. When we got closer, the submerged cross beam hit sandy bottom and the boat went upright. Just a little further and I could stand. I drug the boat up to the beach.

Quite a bit of damage - one hull split up front (luckily near the top) one ama float torn completely loose and the other ama float was dangling.

Another power boater (who also sails) saw the whole thing and had come up just after the damage had been done. He was kind enough to gather the loose items floating around. As such, I only lost a bailing scoop

At the beach, I used a small bucket the second boater had loaned me to bail most of the water out of the cockpit and then I removed my rudder. I prepared to lift the boat up on its side. It will sit on its side with one beam end, the rear of the boat and the tip of the mast on the ground. This is how I attach the sail to the mast during boat assembly.

This time, I would say it had more than 10 gallons of water in the normally sealed forward 1/3 and at least 5 gallons in the rest of the boat as I lifted it. It only took two tries. Water gushed out of the split up front. I took down the sail (I left the mast up). After the front had mostly drained, I put it back upright and finished bailing the cockpit. I put all of my loose stuff on top of the boat, and headed back. At first I went a little way under paddle power. After confirming I had control, the second boater did a great job of tossing me a rope and giving me a tow across the channel. I had to paddle the last little way down and between the docks to my launch site.

Repairs will not be hard. I will probably do some upgrading of a few items (including adding more permanent flotation, especially in the "kind of sealed" section up front) while I am at it.

I really did not like the boat handling with the bigger sail. The ama floats are just not big enough and the extra weight also hurts. I might have been above to make it work in that wind on the pond, but with the chop in the channel (plus the cold water and current making recovery a challenge), I am not sure I had much chance.

I thought I would be able to ease on the power after I got some speed. However I greatly underestimated what an unstable pig it would be while trying to accelerate from 2 kts to 6 kts. The speed of how the planing ama just stalled out got pushed down that far really took me by surprise.

 

[rcnesneg]

Sad to hear about all the problems. Maybe it's an opportunity to make better parts! Pictures of the damage?

 

[P Flados]

No pics. Since I always have such a mental list of items that need repairs or upgrades, I never even think about pics before I dive in.

I kept this thing really light so I could "hand launch" even if I have to carry the assembled boat a short distance by myself.

I also used lots of "scrap" material.

The boat has plenty of strength for sailing loads, but it is wimpy when it comes to rough handling.

I actually found 4 locations (3 were minor at less than ~6", one was bigger at ~12" long) where the thin (~0.1") wood strips on the sides (no fiberglass on the sides) were split. The fix for the splits is easy. I just work epoxy into the split, clamp across the split to prevent an offset joint and let it cure. Sometimes I also have to fix one of the vertical stringers glued to the inside surface. I fixed all of the splits yesterday and made some progress on the "make it better" list.

Since the boat is just a "test platform", I choose to leave it light & wimpy and not worry about the need for occasional repairs.

The damage to the ama floats did not surprise me. I was suspicious that they were not rugged enough. I have also been not completely happy with the pivot action (they can pivot up too steep). I think I will try "adjustable but not free to pivot". I would like more ama flotation, but I have not identified any quick fix so I will probably put this item off.

And yes I am doing quite a few "upgrades and general fixes".

However, there is that itch to get back on the water and the more I take on, the more likely I will miss a chance if it is warm and windy on a day I have off.

It is not hard to figure out that I am something of a "glutton for punishment" with respect to my compulsive desire to go sailing even in less than perfect conditions.

Repairs have priority at the moment. Even though I am off till Monday, it does not look good for sailing. Thur, Fri and Sat have good temps but inadequate wind. Wind picks up Sun but temp goes from 62°F to 50°F in the wee hours.

 

[P Flados]

The repairs/adjustments were 98% done and I was surprised by unexpected sailing day. Very windy (see below) and temperature was passable (60 °F or so).

I got a late start due to not expecting wind + warm. I rushed through final fixings, loaded up and headed to Wrightsville Beach. It was close to 3:00 pm when I was ready to hit the water for a short sail (dusk at 5:00 pm).

The wind was close to straight up the channel making for more chop than I like. Periodic bailing was required to offset water coming in over the sides.

I started working my way upwind. I had forgotten the leeboard, and out of caution I started with all foils down (better stability) in the chop / wind.

I found the I had some "tuning problems". The AOA on the starboard ama foil was substantially more than the AOA on the port side. This messed with boat balance with all foils down. After a few passes back and forth, I was shifting overall beam AOA with each tack & was doing better.

While still working upwind, I started pulling up the windward ama foil at each tack. The 2 foil mode (1 ama + rudder) improved boat speed. Once up to speed, balance and overall feel was very good - I was encouraged by the overall feel.

Eventually, I tried some fast runs closer to reaching (still slightly upwind). However I was somewhat cautious - I was a good way from the launch site and with these conditions (wind, waves & cold water), any crash would be a potential disaster. I probably had foils carrying up to 50% of boat weight and it just felt "slick" going through the water. As a wild guess (see below), I probably hit 10 - 15 kts.

About this time, the starboard ama foil loosened up and would not stay put. Normally I would have stopped and adjusted it, but conditions were not good and I was short on time.

I headed back with some straight downwind and some zig-zags to get angles. When the ama foils stayed where I wanted them, the boat control and feel were good. However, the foil was moving & I was having to round up and push it back using my paddle (dicey task in the strong conditions).

With straight downwind, the boat seemed very un-stressed. Apparent wind speeds were pretty low. I could grab the boom and jibe the sail easily with nothing edgy at all. I did have to watch waves & my heading. As long as I paid attention all was good. If not, the nose would bury some in the back of a wave and/or I would get some water in over the side. Even still recovery was no problem.

When at about 45° to straight downwind with both foils correct, the boat wanted to go fast, but the combination of chop and the sail pushing the nose down at times made me too nervous to push hard. Even if I had not been fighting shifty foils, It was probably an iffy day to try for go for full (or even near full) foiling.

When I got back, I found that I had not set my smartphone to record GPS tracks. This is frustrating since I really had some decent runs and wanted to go over the data.

Over all it was a pretty good day to practice boat handling in close to max (for me) conditions. I also found a number of items ripe for improvement and or just tuning.

 

[P Flados]

Today looked Ok for a “just for fun” sail, 52°F and no rain and a forecast of 11 kts wind (slowly dropping with est 3 hrs sailing at 8 kts or above). I loaded up and and headed to the beach.

Winds were light as expected so I went ahead and rigged the bigger sail. As I left the launch point (at 11:0 am), tide was dropping so wind and a brisk tide current were both from the same direction down Banks Channel (from the Northeast).

I headed across the channel with intent to work slowly upwind. I was trying out my small leeboard (originally a sunfish rudder) and one ama foil down. I worked out a good ama AOA toward the end of the first run across and then on the way back caught a ~ 12 kt - 14 kt puff. I hit the peak boat speed for the day (8 kts SOG, probably a little higher SOW given the current).

I pretty much spent the afternoon going back & while forth playing with foil / leeboard combinations.

 

[Doug Lord]

Now go have a Merry Christmas and a Flying New Year!

 

[Will Fraser]

What is the latest on this exciting little project?

 

[P Flados]

Waiting on work to ease up and waiting on warmer water.

It wont be long now.