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New design project


Kudzu

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Sneak preview of something I am working on. I LOVE the traditional Greenland style even though few of my boats have it. The success of SHAD has motivated me to explore this styling more. I have also been reading the writings of Ken Taylor who lived in Greenland and brought back a kayak that is often referred to as the father of the modern kayak,  The Igdlorssuit kayak. I had a computer file of the boat and decided to look at it again.

 

I started with a model of the original. But the stability of the original was so low, I had to modify it if I ever wanted to paddle it. I slightly stretched, widened and flattened the V in the hull, but only slightly. I hope of maintaining its good qualities. Here is what I have at the moment and I think it is just beautiful! Still lots to do to it but wanted to get a little feed back.

 

If/when I decide to build it, I have some new ideas so this may be a test bed. If I can find a place to store another boat!

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That's a beautiful boat! It appears to have a little more freeboard and higher ends than Shad. Would it get blown around more than Shad or is it deeper in the water to resist that?

 

I prefer a low bow and stern, counting on the foredeck to shed waves before they reach the cockpit. I also like low freeboard, and less length - around 15 feet - but that's just too pretty to resist!

 

Please keep us informed as you play with this design.

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Woodman. while i live close to the ocean most of the time i would be paddeling the Neusse river by Havelock, NC. the water can be dead calm one minute and have 4 foot white caps the next if a Tstort pops up. a boat like the above looks like it would do well enough to get me to shore in those conditions.

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An Iggie!! I'll buy plans if you continue on with it, hope you do. Many kayaks trace their ancestry to this boat. What were you thinking of for the final dimensions?

 

I have a couple different sets of drawings for this boat, including a S&G version, but have been working on a set of patterns based on the 1921 SW Greenland boat that Norman Skene drew the lines for.

 

I have the frames and gunwales cut for the Shad I'm building for my son and the Curlew I'm doing for myself from the offsets in your book but now it's too cold outside to finish building ( I have no garage ). Cutting frames for another boat or two will keep me occupied during the winter and in the spring we can have a lashing and skinning frenzy then we'll have plenty of boats to play with!

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I am amazed at the interest this boat has. Posted in different places and it generates a lot of interest everwhere. It has moved to my build list but as I said before I have other things more pressing, so it will be a while, as much as I hate it.

 

Chris, it hard to say but from what I read about the other copies of the Iggy they are supposed to be excellent rough water boats and turn very quickly. The tracking is said to be anywhere from OK to awful in flat water but perfect in rough water. It has a lot of rocker so I suspect it doesn't track well. Shad has good tracking and turns well for flat water, I haven't had it out in choppy water yet. Our water conditions are either to much or near flat. Not much in between.

 

I have been playing with the idea of a retractable skeg from some time. None of the boats has really needed one so I haven't pursued it. But I am thinking that the Iggy (I need a name for it) could benefit from one. I have been reading about placing a skeg much closer to the center of the boat and I am intrigued by what I am reading. I have a really great design for the skeg box. I just have to work out details for using it on a skin boat.

 

One thing I did find that surprised me, I ran the resistance figures through the software. Put it and Shad on a graph and the Iggy would never show up. I couldn't figure out the problem till I deleted Shad. They graph lines were on top of each other. The two have virtually identical resistance figures.

 

 

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For those of you interested, the "Original Iggy" was designed as the following.

 

If you want to look for yourself you will need

 

Free!Ship 

http://www.softpedia.com/get/Science-CAD/Freeship-Plus.shtml

 

The Model

http://personal.inet.fi/koti/tonivee/KOG/models.html

 

 

Project : Illorsuit, EK 1959, Ken Taylor's kayakDesigner   :Created by   : Toni VäkipartaComment : Rough model by data from webFilename   : C:UserscmDownloadsKOG_072B-Illorsuit.fbm

Design length : 16.562 [ft]Length over all : 16.554 [ft]Design beam :   1.745 [ft]Beam over all :   1.745 [ft]Design draft   :   0.403 [ft]Midship location   :   8.281 [ft]Water density : 62.428 [lbs/ft3]Appendage coefficient : 1.0000Volume properties:   Displaced volume : 3.184 [ft3]   Displacement : 0.089 [tons]   Total length of submerged body :   13.685 [ft]   Total beam of submerged body : 1.592 [ft]   Block coefficient   :   0.3622   Prismatic coefficient   :   0.5067   Vert. prismatic coefficient   :   0.5636   Wetted surface area   :   17.379 [ft2]   Longitudinal center of buoyancy   : 8.110 [ft]   Longitudinal center of buoyancy   :   -1.245 [%]   Vertical center of buoyancy   : 0.271 [ft]Midship properties:   Midship section area : 0.459 [ft2]   Midship coefficient   :   0.7148Waterplane properties:   Length on waterline   :   13.685 [ft]   Beam on waterline   : 1.592 [ft]   Waterplane area   :   13.998 [ft2]   Waterplane coefficient :   0.6426   Waterplane center of floatation   : 8.220 [ft]   Entrance angle :   12.963 [degr.]   Transverse moment of inertia : 2.013 [ft4]   Longitudinal moment of inertia :   123.65 [ft4]Initial stability:   Transverse metacentric height   : 0.903 [ft]   Longitudinal metacentric height   :   39.110 [ft]Lateral plane:   Lateral area : 4.107 [ft2]   Longitudinal center of effort   : 7.908 [ft]   Vertical center of effort   : 0.240 [ft]

The following layer properties are calculated for both sides of the ship:|   Layer   | Area | Thickness | Weight |  COG X  |  COG Y  |  COG Z  || | [ft2]  | | [tons] | [ft]   | [ft]   | [ft]   ||-------------------------|--------|-----------|----------|---------|---------|---------|| bottom   | 13.450 | 0.000 |   0.000 | 8.518 | 0.000 | 0.166 || chine | 14.001 | 0.000 |   0.000 | 8.404 | 0.000 | 0.514 || deck   | 17.382 | 0.000 |   0.000 | 8.453 | 0.000 | 0.693 ||-------------------------|--------|-----------|----------|---------|---------|---------|  Total 44.833   0.000 0.000 0.000 0.000

Sectional areas:

| Location  | Area ||   [ft] | [ft2]  ||-----------+----------|| 1.642 |   0.012 || 3.284 |   0.102 || 4.926 |   0.250 || 6.568 |   0.400 || 8.210 |   0.459 || 9.852 |   0.393 ||   11.494 |   0.233 ||   13.136 |   0.089 ||   14.779 |   0.000 ||-----------+----------|NOTE 1: Draft (and all other vertical heights) is measured above the lowest point of the hull! (Z= -0.132)NOTE 2: All calculated coefficients based on actual dimensions of submerged body.

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Somehow I also remember from some years ago that Current Designs modeled their design Caribou S on the "Iggy"

 

http://www.cdkayak.com/products/template/product_detail.php?IID=154

 

If you read the comments on Paddling.net it had a lot of problems with weathercocking and really need a skeg.

 

http://www.paddling.net/Reviews/showReviews.html?prod=329

 

Kajak Sport has a drop in box already made

 

http://www.kajaksport.com/www/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=56&virtuemart_category_id=7〈=en

 

pdf file on details

 

http://www.kajaksport.com/www/index.php?option=com_phocadownload&view=category&id=1&Itemid=117〈=en

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I have been asking around about the Iggy and copies and I am getting hearing the same thing over and over. Makes me wonder if why. And it really makes me wonder why a bit outfit with big money invested in a mold would put out a boat that weather cocks? Did they not test the boat?

 

But, everyone seems to say the same thing about all or most of the copies so it makes me wonder if it is a characteristic of the strong V hull shape or just all that rocker? 

 

I wish I had photos of the skeg design. Easy to build with minimal skills. No cables to jam. Easy to repair in the field. It has a bungee pulling it down so if the cord breaks  the skeg extends. It is one of the cleverest designs I have seen.

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THAT is the one I copied mine after. I had forgotten it was Ross's design! Now I can give him credit. That, in my opinion, is one of the best designs I have seen. I modified it just slightly and I have replaced skeg and bungee with no problem. If you put a spare in your boat you could replace it should you need.

 

I had never considered putting a skeg in the stern as an assembly but I am sure it could be done.  But I don't want a skeg all the way at back. It will really lock the back end and down it would make it hard to turn. I have been reading about skegs located nearer the center of the boat with some very interesting results. I don't want to give away all my secrets just yet, but if I build an Iggy like boat, I am going to try out the idea on it.

 

So far, the only one of my boats that could use a skeg is a Curlew IF it has a really small paddler in it. Had a 100-105 lb lady in it and the stern would come out of the water in the waves because she just didn't sink it enough. She was inexperienced and it was darting around like a sit and spin with her. A good paddler would have done better but it wouldn't have been fun.

 

But that is just a case of the wrong boat choice. But from what I reading about the Iggy, i think a skeg is mandatory. If I find my design doesn't need one i just won't use it and will leave it off the plans. 

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The closer the skeg is to the longitudinal center of rotation, the more it affects side drift in a wind.  If directional stability is needed, then the size has to increased.

 

Nearer the stern, the area can be reduced to provide sufficient directional stability, plus a smaller degree of lateral drift.  (I'll have to read up on the naval architect's vocabulary for the air vehicle analogs.)

 

Jeff,

What you "need" is an experimental mule with four or five skeg receptacles ranging from the boat's design CG to the stern.  The construction part wouldn't be to much more difficult if the manual retraction/extension is eliminated.  After about 15 seconds of thought and no sketches, I would start with a long trunk from just behind the cockpit all the way to the stem, either with a series of slots where a skeg could be slipped in and secured with a wedge, or build skegs into the trunk from the start to be deployed one at a time.  Some minimal ballast might be needed forward of the cockpit to trim the boat.

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Jeff -

 

I once retrofitted a skeg in a CLC design boat that was very prone to weathercocking (an early Cape Charles model long since superceeded by the Chesapeake).  Worked great.

 

My question is: for a SOF boat how would you handle the sizeable hull penetration? Not a problem on a wooden boat with the trunk epoxied to the hull, but the fabric introduces a special challenge.  Since the frame can generally move and flex within the skin wouldn't there be a lot of stress where the fabric is attached to the frame/trunk? Seems like you would need something like an external piece that could be screwed onto the bottom matching the base of the trunk with the fabric compressed between. Anyway, an interesting problem.

 

BTW, I feel that the ability of the frame and skin to flex and give (and move independently to a degree) is a material advantage of skin boats.  My experience is mostly with a Klepper folder, but the design is similar. Especially in rougher water the skin boats move easily with the waves rather than fighting through them.  It least it seems that way to me.

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It should be easier to attach a skeg as a fixed rudder on the stern rather than in an internal box. It would not be as attractive as an internally mounted skeg, but it could be retractable or it could be built shallow enough that it clears the water when the boat is leaned.

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The fishing kayak is the only one I see putting one on...

I have spent countless hours. Fishing from my skin boat , some times up to 6 hrs. But the best feature without question is the rudder.... It never fails a breeze is present while trying to maintain a position...Well the rudder aids in a controlled trolling position if you want to cruise the shore down wind it is great..You don't have to keep correcting paddle strokes in a gentle breeze....

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I use a rudder on an old Hydra Solo (17' x 22" poly kayak) not as a rudder, but as an adjustable skeg. I disconnected the foot control lines, attached an extended arm across the rudder head, and ran lines to small jam cleats on each side just forward of the cockpit. It's ugly, but it lets me adjust and hold the rudder/skeg angle for cross winds, currents, and poor paddling technique. Obviously, a boat designed to go straight shouldn't need either a skeg or a rudder - a little lean and a little shifting of the stroke will turn most anything - but for a boat that's designed to be "maneuverable" or is poorly designed it can make straight-line cruising pleasant.

 

It should be possible to attach a rudder to a SOF with less chance of leaks than a skeg. You just have to close your eyes if you're paddling facing the back of the boat. Come to think about it, the Iggy is such a beautiful boat, it might be sinful to put a rudder on it.

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