MyPaipoBoards Forums

I measured the displaced volumes and calculated the buoyancies (using seawater density 1.025 g/mL) of three boards: Austin 50", Malama Kai 47" and Hot Buttered 40.5" bodyboard.

Malama Kai 47"
displacement 13L
mass 3.6 kg
buoyancy 21.4 pounds

Austin 50"
displacement 18L
mass 3.6 kg
buoyancy 32.6 pounds

Hot Buttered 40.5"
displacement 20L
mass 1.58 kg
buoyancy 41.6 pounds

All three boards have enough buoyancy for low-speed, non-planing takeoffs, but differ dramatically in duckdiving and hold-down scenarios. (I just fixed the kg/lb conversion)

Ted,

I've attached a graph that compares volume by height and maximum thickness for a range of boards. Thickness distribution as well as maximum thickness are obviously important.

How are you measuring volume?

Bob

attachment=0]Summary_chartx.xls[/attachment]

Board Volume length thickness
Huie 20.78 54.375 2.000
MM1 30.07 53.25 2.812
MM2 20.48 53.25 1.875
MM3 16.38 53.25 1.625
PG_original 19.48 53.25 1.625
PG_edited 18.36 53.25 1.437
PG_Twedited 20.79 53.25 1.437
Squaretail 25.76 64.25 1.625
Paipo w finbox hump 25.96 64.25 1.625
Wood paipo 9.06 51.125 0.687
Roundtail 26.97 72.25 1.625
DeepArc_roundTail 24.85 64.25 1.625

Bob,

I filled a trash can with water and shoved a board in until it bottomed, marked the waterline on the board, refilled the trash can with a liter bottle, flipped the board over, dunked to waterline mark, refilled and added the two replacement volumes.

The full dimensions of the boards are:

Malama Kai
47" x 18.75" x 1.38" (grossly, 1216 cubic inches = 20L)
displaced volume 13L

Austin
50" x 19.25" x 1.75" (grossly, 1684 cubic inches = 28L)
displaced volume 18L

Hot Buttered
40.5" x 20" x 2" (grossly, 1620 cubic inches = 26L)
displaced volume 20L

Ted

Ted,

Thanks. I don't completely understand what you did - so my questions

1) "I filled a trash can with water and shoved a board in until it bottomed" - So the trash can was completely full, then you get your board and push it down until the nose or tail contacts the bottom of the tarsh can?

2) " marked the waterline on the board"- ok

3) "refilled the trash can with a liter bottle" - do you measure the amount of water you put in? does bottle size matter as long as you know how much goes in?

4) "flipped the board over, dunked to waterline mark" - by flipping it over, if you stuck the nose in first, this time the tail goes to the bottom?

5) "refilled and added the two replacement volumes". - so you ned to know how much water you had to put in on both ccasions?

Yo can see why I gave up science at school.

Tonight's reading:
http://www.swaylocks.com/forums/calcula ... ies?page=1
http://www.swaylocks.com/forums/surfboard-volume
http://www.swaylocks.com/node/1024289

Bob
, refilled and added the two replacement volumes.

Bob,

You understand the ideal procedure (fill vessel completely, completely submerge item, measure displaced volume by catching overflow or by measuring refill required). My procedure is complicated because the trashcan is too short to allow complete submersion of the board in one go. My description could be more explicit.

1) "I filled a trash can with water and shoved a board in until it bottomed" - So the trash can was completely full, then you get your board and push it down until the nose or tail contacts the bottom of the trassh can?
Yes.

2) " marked the waterline on the board"- ok

3) "refilled the trash can with a liter bottle" - do you measure the amount of water you put in? does bottle size matter as long as you know how much goes in?
Yes, measure refill amount. It doesn't matter what size bottle or how you measure.

4) "flipped the board over, dunked to waterline mark" - by flipping it over, if you stuck the nose in first, this time the tail goes to the bottom?
Tail goes in, but board only gets stuck in far enough to submerge previously unmeasured volume. Tail will not go to bottom unless the board length is twice the depth of the trashcan.

5) "refilled and added the two replacement volumes". - so you ned to know how much water you had to put in on both occasions?
Yes, add front volume and back volume.

See the video: http://youtu.be/O5AzKfjBtMI

Ted,

Many thanks, much appreciated,

Bob

Hey Ted, how is the austin for duck diving-I have been thinking about getting one but have grown attached to the submersibility (dont think thats a word but you know what I mean) of the all wood boards-
are you able to duck dive them or does one take a thrashing kicking out thru whitewater?

thanks
flojo

Flojo,

The Austin 50" (thinner than stock model), with 32# of buoyancy, is OK to duck dive. I am a lousy duck-diver and weigh 154#. The Malama Kai, with 21# of buoyancy, is easy to duck dive, but still has enough float for sitting on the board and resting.

Buoyancy, in the range of 20-40#, involves a tradeoff duck-diving versus self-rescue capability.

My next Austin will be a 50" with nose bobbed to 46" and maximum thickness of 1.5", aiming for about 25# of buoyancy.

Hey Ted, thanks for the info-i weigh 190 and am also a lousy duck diver -the malama kai sounds interesting I am a long time standup surfer who is getting really interested in paipos both wood and fiberglass but I really dont know anything about them- I have always preferred thinner boards and when I look at the profiles I have seen of the austins I am kind of put off by how thick they look in the tail area-i guess that thickness has a purpose like lifting the legs out of the water when planing or something like that but my ignorance on the subject is monumental to say the least----thanks for the info

flojo

Flojo, Paipo boards are thicker in the back because that is where most of the rider's weight is. On standup boards the rider's weight is in the middle of the board.

Floyo, take a look at the S&S RPM boards -- there are some tail views in this thread that are thinner.
http://mypaipoboards.org/forum3/viewtop ... =rpm#p2357

The baseline Austin is a multipurpose design that I have ridden in many different waves, East Coast, West Coast, PNW, HI, Costa Rica and Puerto Rico. The basic design has pleased me for quite a while. But, I also like a thinner board so when the time came to park a couple of boards in the tropics due to increasing airline luggage issues and cost, I went with a board more optimized to those conditions. And love it in those conditions. My thickest board, a bit fuller than the baseline Austin, built by a shaper in Maryland, is now parked at a friend's home along the Space Coast, in Florida, for the generally weaker waves there--I need the extra float to catch waves. I also keep a baseline Austin (the first one made by Austin Saunders) and an S&S RPM model at my home for the range of conditions here on the East Coast and for the occasional trip to the PNW, HI or elsewhere.

If you are interested in a thinner, slightly narrower Austin then just give him a call and ask for Rod's S&S RPM. If you deviate in length (50 inches) then be sure we and or he talk about the plan shape adjustments.

Flojo,

You should try to ride as many paipo as possible - some are all purpose, like Rod's higher volume Austin, but most feature quirks due to rider style or local conditions. If you get to the Big Island in the winter, you're welcome to try my boards.

well that makes sense-rather obvious-thanks again

thanks rod and ted for your responses- my above, short reply was to the info ted gave me about the placement of thickness-for some reason, I did not see rod's reply nor teds kind offer-Rod, thanks very much for the advice and info-and ted thank you for the offer I live in northern california, and can get in some pretty strong waves but truth be told, I usually surf 6 ft and under--so I am looking for a board that best fits those conditions--

Style and experience and the types of waves ridden are all factors in determining what different people like the most. One guy found an HPD (2% float) to be his nirvana for paddling out and riding Ocean Beach, San Francisco... tons of duck diving and currents there in big surf as you know. On the other extreme is Skiff who has a big ass floaty paipo but he boats out to his point breaks. Think you will like the S&S RPM for your conditions but try out different board types to see what is best for you.

Flojo,

I live in Fairfax. I surf at Ocean beach quite a bit. Id' be happy to show you my board. There are pluses and minuses to all boards. Some boards are better for different breaks. My board is a"floaty" board. I was 20 pounds heavier, when I had it built. So it is pretty thick. There a lot of benefits to floaty boards. I got caught in a rip at Ocean beach this fall. I went further out than I have ever been. I could barely see people. If I didn't have a floaty board I probably wouldn't have made it in. It is great for chasing down peaks at OB. Also you can get into the wave earlier and catch waves you couldn't catch with a thin board. It is perfect for the point and reef breaks in Santa Cruz.

However that said, it can be a bitch to duck dive. If a big wave breaks in front of me or big powerful wall of foam comes rolling in, I ditch the board and dive. I am going to build a couple slightly narrower and thinner boards for places like Chronkite especially for the shorter period summer swells.

Let me know, If you want to see it or my thinner wood board.

ok-jbw-thanks for the info

Well so far my SDF board,no1( see it in the building forum) has proved pretty flawless, I have surfed it from 1ft weak welsh waves to double over head California heavy beach breaks. surfed head and a half ocean beach too.
I managed to do a road rip and scored rincon head high (barreled first wave) and then on to knee high malibu which it competed well with a couple of sup's who were trying to take everything.
So i feel i have a board/design that works in everything.

I really put this down to the concave/V and chine rail I stole from tom wegner and the alaia's, it floats me about the same as my old bodyboards, duck dives super easy and is only 44"

No2 is on the way!! (nothing wrong with no1, just got the bug!!!)

Flojo,

I live in San Mateo and generally surf between HMB and SF. I have a Xylem 48" Malama Kai and a HPD (as well as lots of surfmats). You're welcome to try either of my paipos so if you ever want to meet up and surf please let me know.

thanks !