Sweet Rhode Island Red
I prefer the pod.
So do I 😊
Yes, Pro the Pod, too ,
I like the ama also a lot , look a lot like one of our favourites ...........good water shedding properties ,... and…. quick plywood construction
Hi Chris
I don’t know if I am being over cautious due to my recent experiences but I am nervous about the effects ama and by extension pod drag on steering. Imagine being hit by a sudden gust and the pod digs into the water. This may cause him to bearaway worsening the situation. Additionally to counter this you will want to go forward and outboard, is there not a danger of running out of seating platform.
I think I would prefer one of your supper CNCed hydrodynamic safety amas and parallel seating platform.
Have you done any calculations of crew position effect on trim? a 24’ vaka sounds like a lot of hull to trim
Tink
There are certainly concerns about the effect of the pod on steering. But its not going to come into play until the ama is 28” above the water—a point where I’m getting worried about stability.
Of course that assumes flat water. We’ll see how it works charging into chop.
I have not run any calculations on steering, but SRIR is only 3’ longer on the waterline than Proud Mary—but should have more lateral area because the V’ed bottom will sit deeper than a flat bottom.
We’ll see if that makes any difference…
Hi Chris,
I have not run any calculations on steering, but SRIR is only 3’ longer on the waterline than Proud Mary—but should have more lateral area because the V’ed bottom will sit deeper than a flat bottom.
Well, I now have some GPS data on PM, not that great, at best it does 65* to windward. :-(
I think you might need more lateral resistance as well, but not sure how much, maybe V’ed bottom and extra length do it…
Steering is the one thing I think you’ll be fine with! (famous last words…)
Please see PM thread for more info.
I must say I’m loving SRIR, and hopefully with a few more tests on PM you’ll be able to get it right first time!
Okay, the mast is back in the hull. The rig stays up when caught aback, because there’s a line tied around a puck a the extreme leeward edge of the pod, wrapped around the mast. Now I can cant the rig to windward (or leeward, if the mast is stepped further to windward). Its going to induce some bending, but no more than the slot does. Its not shown yet.
I have been adding lateral area by making the pointy bottom of the boat deeper. It now draws 19” at 1200lb and the floor is 7” above the waterline. The pod, fully immersed displaces about 1000lb. It has hatchless lockers inside the pod, that drain into the cockpit. Heavy stores go under the cockpit floor.
The deck is a plywood skinned foam sandwich with a raised hand hold/ tie down rail around the perimeter. Its 4’ wide and 10” long
Having no mast or anything on the deck provides plenty of room for scooching or walking around to steer.
I’m designing a rudder/steering paddle based on the one on Equilibre, for security on downwind courses.
This boat could be rigged in a variety of ways! But I like the boomless gibbons/dierking rig that furls around the yard (lowered, on deck). Adding a sprit boom might be cool. I also like the idea of long battens that are parallel to the yard to give it some roach. But it could easily be set up with a crab claw, Pizzey-ish Isoceles sail, jibs, and a bunch of other stuff I’m not thinking of.
I’m really liking where this is going as a simple little, butt and rig steered camp cruiser.
a few more shots…
Here it is with some roach. Battens (rod, like the hobie adventure island’s) parallel to the yard give it 30 extra square feet—for a whopping 150 square feet…enough to get this 16:1 canoe moving.
The lateral area in the water is over 26 square feet—more than 4x Proud Mary’s.
I’ve been thinking about rudders for SRIR.
I’ve sketched a bunch of interesting steering paddles based on the cool one on Equilibre—half rudder (pivots on a shaft) and half paddle (you unhook it and stow it when you are done).
Then I started thinking about Pizzey’s kick up rudders on a bent shaft. The shaft is the pivot point for the rudder, it bends 90 degrees, through a generous radius, and then becomes the pivot for the rudder to swing up. A small line attached to the rudder keeps it from kicking back—like the torque line on Gary Dierking’s motor bracket.
So here’s the new part. Instead of kicking up and being generally vulnerable with the blade horizontal near the water or sticking up in the air vertically, the rudder flips back 270 degrees and stows in the canoe. Now the blade near the bow is safely stowed away. My trick is not to put the kick up pivot axis perpendicular to the mid line. Its shifted about 5 degrees, so that as it swings around it finds its way into the canoe.
On most courses, both rudders would be stowed. But on downwind courses, you could, flip one over (lifting up and back, then tighten the torque line to pull the blade forward. The torque line can be used to tune the position of the rudder fore and aft, to a certain extent.
Its still a system that pierces the water’s surface, but its well protected. The rudder doesn’t extend lower than the keel, which at 1200lb is 19” below the waterline.
The blade is a naca section 12” front to back and 18” tall—at least in this model. There is stilk a litttle bit of the top or the blade showing at full displacement—but maybe not once everybody is aft, on a downwind sleigh ride.
Part of me is disappointed that the foil less boat just got two foils, but you have to go down wind some time.
I’ve been thinking along very similar lines, except on shunting letting the bow rudder float up by itself, and then fastening it under the beam once underway. Trying to think of how to elegantly handle the tiller etc.
It might make more sense in your case to design it so it is easy to (un)attach completely while on the water?
-Thomas
Gary’s comment on Johannes’ circular rocker thread got me thinking a lot about rocker.
http://proafile.com/forums/viewthread/298/P30/#2776
So I thought I’d play around with SRIR’s keel profile. I lifted up the bottoms of the stems a few inches, to reduce forefoot. I added 2 feet of overhang to the boat—so each bow overhangs 18”. So she grew from 24’-26’ because I didn’t want to change the waterline length of 23’ for comparison’s sake.
Then I drew a horizontal, straight keel and connected that to the stem with another straight line, and rounded the corner.
I loved the overall effect, but straight lines on boats can make me a little queasy. It also makes the plywood bend too much in one place which seems wrong both from a structural and hydro POV.
So I left the straight keel and built a very soft spline between the stem and the keel. Okay, now we’re getting somewhere.
The new shape has almost identical displacement but 28 sq feet of lateral area instead of 24. And the cutaway forefoot should make it more sensitive to weight shift—since more of the buoyancy is concentrated in the center.
Anyway, here is a comparison of the old shape and the new, much more marshallese looking shape.
And as long as I was in there messing around, I did a round of refinement on my rudder.
This rudder should only be for courses off the wind where butt steering can’t be as effective.
The thing I like about this design, shamelessly stolen from Pizzey, is as simple as any I have seen.
One of the things I don’t like about outboard rudders is having something hanging off of the boat near the bow. These stow in the canoe by flipping them back 270 degrees. There’s a line going from the front of the blade, just above the waterline to the foreward aka that limits rotation when its down. That line will have some “fuse” in it to allow the rudder to kick up.
I made the blades bigger, which meant some rejiggering of the whole geometry. Its very interdependent!
Anyway, the result is a rudder system with two moving parts per side; the bent tube that acts as the kick up pivot AND the rudder shaft, and the blade/tiller assembly.
Above the blade the front edge is sharp to (somewhat) reduce the spray of a surface piercing foil—shamelessly stolen from Gary Dierking’s leeboard mod.
Maybe it would be possible to adjust self steering downwind by trimming the rudder forward or aft, using the tiller just for small corrections.
I think the last iteration of your SRIR looks gorgeous with those overhanging stems.
They will add a lot of resistance to pitchpooling and give a softer motion when going through waves.
I really love your beautifull renderings of proas.
Cheers,
Johannes
I think the last iteration of your SRIR looks gorgeous with those overhanging stems.
They will add a lot of resistance to pitchpooling and give a softer motion when going through waves.
I really love your beautifull renderings of proas.Cheers,
Johannes
That’s something that I have never been able to understand. I have seen many times that a very curvy/springy keel line with long overhang is considered a good thing for pitch polling or pitch control…
For me, for the same overall length, a boat with a flat keel line and “square” bows will be much more resistant to pitch polling.
The pitch angle you have to get to for those overhangs to start to get into the water and generate lift, the straight keel hull will already have a lot of buoyancy forward by much more hull volume in the water.
If you want to avoid pitch polling, you have to attempt to move the center of buoyancy forward as much as possible for the minimum pitch angle.
How are long overhangs better for this end result?
Cheers,
Laurent