Scampi
Very very nice boat
it just might go well with some rudders like this
http://www.tacking-outrigger.com/proa_rudder.html
(I need to modify the drawings a fraction for a smaller diameter drum, this way lateral forces on the blade would be above and below the drum, reducing wear on the drum and making it easier to pivot)
A small boat like this, is likely to operate in shallow coastal waters, thus a non-breakable rudder system of some sort would be preferable.
Another option (maybe it makes no difference) would be have the leepod a removable component, allowing the cockpit to be increased in area and still maintain 8ft trailering beam. Dont get me wrong, not trying to be picky, these sketches are extremely good
n peter evans
Hi Peter,
I like your rudder idea. I have struggled with these same issues. Having the rudders kick up seems like a no brainer feature to have, but they have a lot of downsides on a proa.
The centerboard slot causes a lot of drag. Twice.
As you point out, the rudders might not be straight when they kick up. The wedge cut out of the top helps! I used this same solution on one of my Walap Beach Cruiser concepts. But then the trailing edges of the rudder are trying to penetrate the bottom of your boat.
Newick/Brown dagger rudders kick up a little too. But they use simple crush blocks. And when you do hit something you can pull them out to repair them, not swim under the boat. Have you checked out Sven’s awesome description and photos?
http://proafile.com/forums/viewthread/27/
The best kick up rudder idea I have seen is Michael’s monoproa. The fan shaped centerboards find their slots because they are always in them. And it steers by moving the CLR fore and aft.
http://proafile.com/archive/article/rozinante_ii
I imagine having two wheels. One adjusts the total amount of board down, and the other adjusts the ratio of area fore and aft. I’d love Dave Culp’s assessment of this scheme.
But what happens when the front one is down part way and you hit something?
On the subject of the pod: I want one. I respect not wanting one, but I do on anything more than a beach cruiser. I know that sickening feeling of diminishing stability on a beach cat as the windward hull comes up high, and eventually the CG travels across the CB and it feels the urge to be upside down. Check out sven’s post about stability on Pacific Bee.
http://proafile.com/forums/viewthread/25/#214
If you want a more dynamic example, check out Jzerro being gently put back onto her feet by the pod. It happens just before 1:40
http://www.youtube.com/watch?v=gmVflYLPOhY
I’d rather tilt Scampi over on the trailer than make the pod removable.
Take Care,
Chris
Here are a couple more renderings. One of the interior and another of my sliding hatches, along with a cross section through the split junk wing thingie.
Hi Chris,
I really like this boat. I’ve seen a lot of cool stuff on this forum, but nothing that looks as right as this.
The images with the green deck on the previous page are what got me hooked.
What are you planning to do with this boat?
Best regards,
Russell
Hi Russell,
Thanks so much. I’m totally honored that you dig my design—or cartoon of a design. I’ve been a fan of your work for decades.
Do you like the split junk wing or the balanced lug? What do you think about the unstayed mast? Think that it’s far enough to windward? Any other tips or thoughts?
These studies have just been for my amusement. I’ve thought seriously about building a Madness kit. But its a lot of boat to build and pay for. A 24 footer is still a lot of boat, but its probably less than half of a 31 footer. So all of these designs have been about what you can do with 24 feet. Also, my garage is 26 feet long.
Having said that, I’ve been working on this instead of getting my Wa’apa rig and foils built…
Scampi’s indoor/outdoor arrangement, combined with a high sided, dryish cockpit felt ripe for proafiation. Plus there were a bunch of nice themes and details for me to quote in my design ; ) I decided that the sliding hatches were too much of a big boat solution. A scampier solution would be fabric hatches. It looks better with the cabin top uninterrupted by openings, but it seemed like a squeeze to get in that way. Plus you can’t stand in the companionway and steer.
I’d love to find a way to get this built for real, but that would still take a lot of money and time for both for the boat and the proper engineering that would go into making her a light, sturdy, sweet sailing little camp cruiser/day sailer. Maybe there’s some way it could be built as a class project for the NBS or something like that. I’d love to start a larger collaboration around getting her built, if folks are interested.
Maybe a 24’ proa would be a nice PT Watercraft product!
Your enthusiasm for Scampi made my day.
All the best,
Chris
As you point out, the rudders might not be straight when they kick up. The wedge cut out of the top helps! I used this same solution on one of my Walap Beach Cruiser concepts. But then the trailing edges of the rudder are trying to penetrate the bottom of your boat.
In theory, there is a way to fix that. On top of the rudder axis, put a T-shaped tab, with the crossbar aft. While the rudder is down, this T moves in a cutout that restricts movement to perhaps 45 degrees either side. Make that cutout V-shaped, so that when the rudder hits something and the top moves forward, there is progressively less space for the T. That straightens out the rudder blade, provided that none of it tries to enter the slot before it is aligned. You would have to remove more than that little wedge at the top.
The best kick up rudder idea I have seen is Michael’s monoproa. The fan shaped centerboards find their slots because they are always in them. And it steers by moving the CLR fore and aft.
http://proafile.com/archive/article/rozinante_ii
That will work only while you have wind in the sails. It will not help you steer under power other than sail, for example in harbour (unless you trust this steering method enough to sail into your slip). The design would need some other arrangement for that.
Regards
Robert Biegler
Hi Robert,
I totally agree on both counts. The cut out in the top of the rudder blade might allow enough travel for a tapered thing to straighten out the rudder. And the fan shaped centerboards won’t work without a sail, or at least a sail-like CE. Maybe it would be possible to modify the little 2.5hp outboard to have a rudder thingie glued or clamped on it, and steer with the outboard under power. Or maybe there’s some way of mounting the outboard pointed somewhat towards the vaka so that the centerboards can steer. That second one sounds kind of inefficient.
As if things weren’t complicated enough, maybe the boards could go in the way tornado boards do—dagger in from the top but with a trunk to kick up into.
I’m very interested in your thoughts about the split cambered junk on Scampi, where the fore panel acts like a jib, aft panel wraps around the mast. In your aerodynamic opinion, is this a road that looks interesting? What do you think about its chances against a similarly sized lug sail?
The lug has a lovely saltiness and simplicity. And with a barber hauler, rigged to the center of the leeward edge of the cabin top, you might get a bit of vang to flatten it out on beam and broad reaches.
Best,
Chris
I’m very interested in your thoughts about the split cambered junk on Scampi, where the fore panel acts like a jib, aft panel wraps around the mast. In your aerodynamic opinion, is this a road that looks interesting? What do you think about its chances against a similarly sized lug sail?
I don’t know how much my aerodynamic opinion is worth. I am willing to risk my own money and time on it. For everyone else, remember that my advice is free, and worth every penny you pay for it, perhaps even more than that!
My experience with lug sails is limited to the one on my Paradox. For whatever reason, that sail has developed a tightly cupped luff and leach, and that is an absolute disaster going upwind. A first-time sailor on an Yngling who sheeted his jib to the midline of the boat, because he didn’t know any better, still went faster and pointed higher. My Paradox points higher and goes faster on port tack, with a great, big mast messing up the leeside flow, than on starboard. The reason seems to be that to keep the luff from fluttering on starboard tack, I have to oversheet so much that it is worse than the effect of the mast on port tack. I don’t know whether it’s age or whether the sail maker was just not familiar with lug sails. On port tack, the mast changes the orientation of the luff so that I don’t have to oversheet.
I think the people to ask are the canoe sailors, many of whom do use standing lugs. The persistence of the rig suggests it can be better than it has been for me.
If I can’t find someone to take the Paradox off me, I plan to put either a split junk or a soft wing junk sail on her. The drawback for my purposes, but an advantage for proas, is that the centre of effort is close to the mast. Paradox needs to load up the rudder, which provides most of the lateral resistance. Either of the rigs I consider will require me to add a mizzen to move the centre of effort aft again.
However, if my model tests work out, I’d rather test the biplane sloop rig on a beach cat-sized proa. I still need to make the jib for the model and rig the sheets, then I can test next time there is a suitable wind and temperature high enough that the sheets don’t freeze solid. And I still have to work out how to transport the wing on the bicycle without damaging it. So don’t hold your breath.
Have you considered putting a long pram hood on the weather side of Scampi’s cockpit?
Regards
Robert Biegler
Just a small update, have improved the idea a fraction
most loads on a rudderboard would be to leeward and to windward, with lesser loads aft. Having the drum smaller allows the board to take these loads above and below the drum. The drum is just there to keep it in place and thus can be a loose fit.
There is a concern that if the rudder is off centre, and a hard grounding occurs, the rudder may catch. My thinking is that as the rudder moves aft progressively, the board straightens progressively. The loads keeping the rudder board tilted left or right would be tiny compared with the huge forces pushing the rudderboard into the case. With the geometry showed below when the board first moves into the case, only a tiny bit of rudder chord is there, this hits the bottom of the slot, forcing it straight.
There are other ideas for proa rudders, have zero problems with other methods, am just putting this idea out there.
With boards at the very end of the hulls, they may be vulnerable to more ventilation, which is probably why Russ Brown had his rudderboards away from the ends ( please excuse my forwardness, I have no doubt he can speak for himself ). Jzzerro, Cimba Kauri etc are large boats doing more sailing in deeper waters, smaller proas of the Mbuli size are likely to sail closer to shore (day sailing etc) and of greater risk of grounding on shallow water.
They say there’s nothing new under the sun.
Apparently that goes for my sail design as well. Check out this laser with a split junk rig where the aft panel wraps around the mast.
Has anyone seen a split lug?
This carbon spared, Irens designed, BJ17 with a lug rig is AWFULLY pretty. Look at the rake on that yard! Thats about 150 square feet. Add another 50-70 or so and scampi should move okay.
Carbon makes a ton of sense here. As do low stretch sails and rigging.
But will a lug rigged proa hit a wall aero-efficiency wise? Or with modern materials on a slender proa, will it fly?
Has anyone seen a split lug?
I have never seen a split lug, but i find the concept intriguing. I prefer the lug over the Junk because of the latter many battens and the associated weight. The lug seems more clean and more aerodynamic efficient. I don’t know if that is the case, but that is my impression.
If it is possible to build a high-aspect high-peaked split lug without the normal “bad tack” where the sail presses against the mast, i believe we finaly have found the perfect proa-sail. Im very impressed by the lug. Its a very powerfull and easy handling sail.
Thank you for giving me something to think about today! I will start reading about split junks. I hope that knowledge will carry over to the lug.
Cheers
Johannes
From a quick Google search.
Seems there is very little new under the sun….
I still believe the is a lot of development left to do on the split lug.
Cheers
Johannes
A split lug should be very similar to a mix of the Balestron rig and the Wharram soft wingsail. The part forward of the mast should work as a very high aspect lugsail/jib tensioned between the boom and the yard. The parf aft of the mast could have a very wide luff pocket and be very similar to the Wharram soft wing sail.
Thank you Luomanen for a very intruiging idea!!!
Cheers
Johannes
The split lug might have a future. Though, Bolger doesn’t seem to like the idea.
The more I read about lugs the more I’m intrigued. And I just LOVE Nigel Irens’ interpretation. The longer the luff, the greater the tension necessary to keep it from sagging. The junk wins there, but maybe the lug can be made tight enough with some spendy, high modulus, modern materials—the same ones you’d want to use on a sloop.
This latest lug rig on scampi, with about the same area as the split junk, uses a mast almost 70” shorter! I’ve shown 4” carbon tube for the mast and 2” for the yard and boom. It looks WAY saltier, too. I’ve restrained myself to a 20% overlap with the mast at the boom. That’s what the Irens ones seem to have. More might help out a proa, I’m guessing, buy moving the CE forward.
Again these are just cartoons, but if they could be engineered to work, there might be a here here.