Author Topic: 12-6' x 30" design tips  (Read 32044 times)

jrandy

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12-6' x 30" design tips
« on: May 25, 2015, 08:37:12 AM »
Hello Everyone-
I need to make a 12'-6" x 30ish" for a larger-framed friend for recreational flatwater use.
I am new to here and SUP, have done some surfboard builds with EPS.
My due date is June 6th and I need to finish it to deliver to his visiting artist. Since we are similar sized, I'll probably make one for myself once I recover from the first one as flat water options are plentiful in my area.

I have a couple questions, thanks for reading.

My buddy tried a Boardworks 'Raven' 12-6. I got to ride a Rave Sports 12-6 'TS'. Both are 30-31" wide with square tails.

1. Rocker: the TS is maybe 1", the Raven 3+inches. How does this affect ride for beginners?
2. Tail width: TS is 10" @ 0 and about 20" at 12", the Raven is 5" @0 and 15"@12 and looks 'tippy' to me. Go big (since I'm already home...)?
3. Post-glassing color: Artist is SUP-savvy will be painting 'decorations' w/ acrylic artist color post-glassing.  What should I use as a primer and they as a clear coat? Should decorations be some other media?

Thanks again, Jim
http://pushheretosavealife.com/
Be safe, have fun. -J

TallDude

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Re: 12-6' x 30" design tips
« Reply #1 on: May 26, 2015, 04:27:35 PM »
1. More is more stable, less is less stable. (1" to 2" tail, 2" to 3" nose) more for open ocean.
2. More is more stable, less is less stable. (narrower tail not always faster) On a wider tail board, V in the bottom of the tail can be the equivalent of a narrow tail.
3. The primer needs to be compatible with the paint. The clear coat needs to be compatible with the paint.
It's not overhead to me!
8'8" L-41 ST and a whole pile of boards I rarely use.

jrandy

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Re: 12-6' x 30" design tips
« Reply #2 on: May 27, 2015, 05:37:52 AM »
Mahalo Talldude!

I am trying to understand the comments about rocker. I am not 'getting' that more rocker=more stable. Could you or someone add some thoughts to this please? The board will be used mostly on calm inland waters.

Any more tips on the painting side would really be appreciated. I will be glassing with RR epoxy and was thinking of getting it to a sanded gloss state before painting. If anyone has a 'brand x'  or paint type + application method recommendation I'd appreciate it. I want to set the artist up to be successful.

The board is for upper Midwest USA summer use and will be stored in a garage for the winter, I don't know if those details affect paint and glassing choices.  Foam is 1.5# EPS, vented, wood center stringer, some combination of cloth, some sort of patch under the pad. I need to review some notes from DW and the latest schedule thread...and get some stuff ordered!

Thanks again, J
http://pushheretosavealife.com/
Be safe, have fun. -J

TallDude

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Re: 12-6' x 30" design tips
« Reply #3 on: May 27, 2015, 08:35:50 AM »
If a board has no rocker and a somewhat pointed nose and tail, it will want to freely rotate about it's axis length wise. Once put rocker into a board, you're distributing the mass away from the axis. This increased rotational inertia resists the turning about it's axis. Like an ice skater in a spin, they move there arms out to slow themselves down. A wider board does the same thing, it moves the mass outward increasing rotational inertia. The board rotates slower, giving you more time to react. There are other liquid pressure forces at work, but for the most part they help increase resistance as the mass moves outward.   

Scan through one of my old posts, and it may answer some of your questions. The painting and priming part is near the end.
http://www.standupzone.com/forum/index.php/topic,18700.60.html
« Last Edit: May 27, 2015, 08:46:04 AM by TallDude »
It's not overhead to me!
8'8" L-41 ST and a whole pile of boards I rarely use.

jrandy

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Re: 12-6' x 30" design tips
« Reply #4 on: May 28, 2015, 05:48:04 PM »
Thanks for the link Talldude!
http://pushheretosavealife.com/
Be safe, have fun. -J

jrandy

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Re: 12-6' x 30" design tips
« Reply #5 on: May 30, 2015, 08:40:46 AM »
Here are my musings so far. Any tips on designing a recessed 'cockpit'? Thanks, J
http://pushheretosavealife.com/
Be safe, have fun. -J

TallDude

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Re: 12-6' x 30" design tips
« Reply #6 on: May 30, 2015, 09:15:41 AM »
What is the CAD program you are using? Did you draw it as a solid?
It's not overhead to me!
8'8" L-41 ST and a whole pile of boards I rarely use.

jrandy

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Re: 12-6' x 30" design tips
« Reply #7 on: May 30, 2015, 11:27:21 AM »
TD-
The 2D was done with Draftsight (free), the 3D was the 2D exported as DXF and stuck into Inventor (courtesy of work).
I extruded the profile into a sled-cut 'blank'  and then did the outline as an extruded cut. It is a solid, but primitive. Then I turned on the ground plane to render the water and made a second copy of the design to guesstimate buoyancy. At 300# (board+rider+accessories) the draw should be about 3", at 360# (previous+dog+extra) 3.5".

Based on the predicted waterline, am I keeping too much foam through the top?
Also, do the 4-fin systems (1 in front, 1 longbox+2 on the rails in back) have any merit for this kind of board? If so, what is a starting point for toe-in and cant on the rail fins?

Thanks again, J



http://pushheretosavealife.com/
Be safe, have fun. -J

TallDude

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Re: 12-6' x 30" design tips
« Reply #8 on: May 30, 2015, 10:40:20 PM »
You know enough about CAD to have a short learning curve with Shape3D. Download the free version. You'll be able to recreate that board pretty quick. I will tell you the volume with every tweak.  If you have any questions about it, PM me.
It's not overhead to me!
8'8" L-41 ST and a whole pile of boards I rarely use.

jrandy

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Re: 12-6' x 30" design tips
« Reply #9 on: June 06, 2015, 08:19:03 AM »
Thanks Talldude. I am more comfortable with engineering-style CAD than the surfboard variety at this time.

I decided to switch from CAD to foam last weekend. Lately I have been making templates from paper taped together, this one I went back to 1/8" hardboard lofted with a flexible batten aka strips of hardboard and a glue gun.

We hotwired the billet into a piece for narrow (<25") boards and one for SUP's (<33") then did the sled cut for the rocker on this board. The blank is split, stringer added, and outline is roughed in. Had a brief panic while setting the stringer that the rocker was flattening. The glue-up was done on a concrete slab. I added some weights center of blank and some wood at points nose and tail and the rocker settled to within a quarter inch or so of intention.

Splitting and outline cutting are more challenging with 6+" thick materials. I should have built a wider shoe for my saber saw to keep the 10" blade nice and vertical. Stringer has a wiggle or two as well.

Work caught up with me and I had to tell the 'team' (artist and owner) that the board is going to be a couple weeks out. They were understanding.

This weekend will be cleaning up the outline and the thickness.

Everyone-Any tips for this build or next time are appreciated. Thanks, J
http://pushheretosavealife.com/
Be safe, have fun. -J

TallDude

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Re: 12-6' x 30" design tips
« Reply #10 on: June 08, 2015, 05:30:59 PM »
TD-
 I turned on the ground plane to render the water and made a second copy of the design to guesstimate buoyancy. At 300# (board+rider+accessories) the draw should be about 3", at 360# (previous+dog+extra) 3.5".

Based on the predicted waterline, am I keeping too much foam through the top?
Also, do the 4-fin systems (1 in front, 1 longbox+2 on the rails in back) have any merit for this kind of board? If so, what is a starting point for toe-in and cant on the rail fins?

Thanks again, J
Sorry J, I totally missed your questions.
1.) 3" I what I usually what I plan for, of course volume and surface area will make it vary. I try to cut the foot wells about that line. Anything lower and you need a drain.

2.) You need extra buoyancy on the front half so the volume distribution looks about right. 

3.) I can't think of a 12'6 I've seen with them. The side bites are just for turning on a wave. They create drag as well. Front and back are as far as I would go.
The side bites / rail fins are pointless on that board.
It's not overhead to me!
8'8" L-41 ST and a whole pile of boards I rarely use.

jrandy

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Re: 12-6' x 30" design tips
« Reply #11 on: June 10, 2015, 11:15:26 AM »
Some mid-build pictures:
1. Showing rocker cut from slab, stringer glued in place, template for reference
2. Outline cut into blank on horses, note defective 'rail' (gunwale?) starboard stern from misguided jigsaw. Port side tapered out.
3. Method for correcting outline- two templates one hotwire. Now board has even inward taper both sides

Top has been leveled (to fix glue-up issue), bottom is next. Then I need to make a plan for blending rails to deck and bottom.

Thanks, J
http://pushheretosavealife.com/
Be safe, have fun. -J

Biggreen

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Re: 12-6' x 30" design tips
« Reply #12 on: June 10, 2015, 07:24:33 PM »
Looking good! I'm always amazed at the amount of foam that starts out in those bigger boards. Hats off to you, TallDude, and supuk Charlie (and others I've omitted) that build those big boards. That's a helluva lot of work that I imagine is difficult to keep straight.

TallDude

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Re: 12-6' x 30" design tips
« Reply #13 on: June 10, 2015, 08:32:25 PM »
Hey Jrandy,
This is a very old post I did, but there might be something in it that could help?

http://www.standupzone.com/forum/index.php/topic,14206.0.html
It's not overhead to me!
8'8" L-41 ST and a whole pile of boards I rarely use.

jrandy

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Re: 12-6' x 30" design tips
« Reply #14 on: June 12, 2015, 04:39:54 AM »
Thanks for the link TD. Maybe I am not using enough Newcastle in my process ?!?
Seriously, nice build and the profiling box was something else.

I got the glue-up errors worked out of the blank, thinking about nose, rails, etc.
I saw this one from Jimmy Lewis while working on mine. Do these bottom curves look like a good starting point?
Thanks, J
http://pushheretosavealife.com/
Be safe, have fun. -J

 


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