I’m thinking about doing a “speed egg” for my next board. Something with fairly simple contours in the 7 foot-ish range that will work in a variety of conditions. I would like to loosely follow the design of this one:
The design is a tri-plane bottom to panel vee through the tail.
From what I can gather the tri plane bottom design is basically a chine around the rails and a flat bottom. at least that is how it is explained on the natural curves website.
This looks like it should be fairly simple to duplicate. I’m just curious if anyone who has experience with tri-planes or chines on mid-length boards can help me a little with the specifics.
How far would you bring the chines in toward the stringer? How deep should they be toward the apex of the rail?
How much vee would you put into a board in the 7’-7’6" range?
I’m thinking a softer 60/40 rail going hard through the tail would work with this in varied surf conditions throughout California and Baja. Does this sound right?
I’m fairly new to shaping/design so any help is always appreciated!!
I’m in the “little-goes-a-long-way” camp. Maybe a 1/10th" panel extending 2.1/2" or 3" in from the rail, and run it all the way to the tail. Real subtle. For fishes and singlefins I blend the chine into the bottom. Then you don’t even need a panel vee unless you’re running more tail than you can turn. I favor a good tuck/edge at the rail.
I think this is what you are thinking about. My board is 8’ x 22" x 2.5" I wanted to add the bevel edge to keep the rail thin.
I drew a line about a 1/4" from the bottom along the rail and another about 3" in along the bottom. The bevel or chine runs up to where the center fin is then it’s fairly flat. I made a nice concave on the bottom that runs flat at the front of the center fin. The photo doesn’t show another inch of foam I add to finish off the rail.
I’ve done these bottoms where the concave section runs down a straight line about 1/3 the width of the board and the bevel runs down the board from that section out to the rail.
That’s exactly the info I was looking for! I actually did that exact chine to vee combo on a mini simmons I just shaped, so it’s good to know I can use the same technique for this board!
RDM - Thats a pretty radical shape! You are right, I think technically anything with three planing surfaces could considered a tri-plane design, although I might be tempted to call that one a tri-concave or a hydro hull! I might need to shape a few hundred more surfboards before I try something like that. For now I think 3 flat surfaces is more my speed ;).
A basic speed egg with a 2+1 or thruster fin layout is a good versatile shape that can cover a wide range of wave conditions. With plugs or boxes in place, you can do some fine tuning after the fact. Here is a link to what might be called a tri-plane hull. I don’t really know the specifics like how much lift to put in the side panels or how wide they should be. I think it depends on the outline, rail foil and rocker curve. Common sense tells me that any amount of lift in the side panels should help prevent catching forward edges.
PS - I’d go with more tail rocker than what is seen on traditional ‘hulls’ as shown in link. A speed egg is a bit different and (IMO) with 3 fins you can get away with more rocker. https://www.swaylocks.com/comment/477717#comment-477717
Not long after I saw that Chris Brock photo, I put a similar bottom on a board I had to strip and reshape, sometime after 1978 before 1980.
The bottom I showed is similar to Bill Stewart’s Hydrohull, I’m not sure how wide his bevel is or deep he makes the concave.
In the past I thought a triplane hull was 3 flat planes, so I’d make a flat center panel, then the sides would be at a slight angle. Kinda like taking a vee bottom then flattening out the middle. I’d do it in thirds, and it was easy for me because I was using 6" wide strips of foam to make my blanks. I just followed the glue lines.
I like a little concave under the nose of my boards, but it’s usually 1/8" or less. I tend to flatten it out by the last 18", and sometimes have a little vee out the end.
I have another question that has come up specifically related to vee. Searching around on sways about mid-lengths I see a mix of boards designed with either vee all the way through the center fin and tail, or vee that just goes through the fins and becomes flat in the last part of the tail. Can anyone explain to me what would be the difference in terms of feel and surfing performance?
I’m also having trouble picturing the process by which a vee to flat tail would be shaped… can anyone enlighten me?
I sketch lines on my boards to help guide me. I guess it would be the same as having the wire frame grid a computer model would draw out but with a lot less lines.
For a board in the 7’ to 7’ 6" range, I wouldn’t want much vee.
Check this image of McTavish out. A few years ago, the transition period McTavish vee bottom was what everyone was talking about. I found this is a book about surfing from Nat Young. I used this as a guide to make an 8’ long egg like shape, but I had the tear drop flat section end at the middle of the fin box. I wasn’t too happy with the first surfs on it, but I pulled it out earlier this year and put in a big Greenough 4A fin all the way back and worked better than I remembered.
