Friday, March 03, 2017

Friday 3 3 17 morning call

Small clean day at Hookipa yesterday, ideal for my customer to surf The Point for the first time. After our session I went to Jeff Henderson's house and let him try my foil setup for windsurfing.
His words after he tried (successfully, of course) made me feel a little better about my slow progress:"this is a tricky setup".

The photos below show the difference between mine and his setup (the boards are laying down with the mast tracks lined up). Notice the following:
1) his board is longer (well, trust me on that)
2) the box for his foil is all the way at the tail, mine is 20 inches from the tail
3) the fuselage of his foil is longer than mine
4) the mast of his foil is longer than mine.

All those differences together make my setup less directionally stable (as I had the feeling) and harder to learn on. Don't forget that my Gofoil is designed (and positioned) for SUP foiling. I am just trying to see if I can use it for sailing instead, mostly for learning purposes (I still think you get much more practice while windsurfing rather than catching waves with the paddle).

4am significant buoy readings
South shore

2ft @ 6s from 217° (SW)           
1.5ft @ 7s from 206° (SSW)
1.2ft @ 14s from 187° (S)
1ft @ 11s from 228° (SW)

A couple of leftover kona windswell readings, but also a couple of longer period proper souths. The map below is from Friday Feb 24 and fetch n.4 is probably responsible for the 14s small energy.
Check the webcams before going.

North shore
4.6ft @ 8s from 69° (ENE)
1.8ft @ 11s from 358° (N)

Considering that yesterday's readings were:
4.7ft @ 9s from 56° (ENE)
1.7ft @ 12s from 344° (NNW)
we can deduce that today it's going to be kinda similar to yesterday, just smaller. Both swells went down a second in fact, and the windswell is now coming from 69 degrees, which is a much less direct direction for Hookipa. It's actually pretty much parallel to the coast.
The map below shows that actually the orientation of Maui's north shore from Hookipa to Kahului is roughly 65 degrees.

This second one though, shows that Hookipa is a bit more exposed with a geometrical shadow line placed at 68 degrees. Don't forget that the higher the period, the more those geometrical shadow lines between emerged land points lose their significance, because a long period swell will be effected more by the submerged reefs, refract around them and eventually end up in places you would not suspect just by looking at a map. They do work much better for shorter periods though (like today's windswell, for example), since these are less sensitive to the bottoms.

A very good example of bottom influenced behavior is the Waiehu coast.
The picture below shows a shadow line from the Mokeehia Island to the end of the Kahului harbor west pier of 332. But you can surf on that side with swells that are more west than that, as long as they're long period and big enough.

This explains even better what submerged reefs can do to swells. Let's imagine there's a big NW swell from a direction more west than what I just said. The swell will refract on Kahakuloa and let's imagine it arrives to the Waiehu golf course area with a direction of 320 (yellow line). In front of the golf course there's a reef (R) that sticks out quite a bit.

The swell will refract on this reef too and bend enough to hit the spots in the area that I circled with the letter W (waves!) and completely miss the area that I circled with F (flat). The funny thing is that can happen even with a swell coming from 335. You think it's gonna get to the F area because it's unblocked by emerged lands, but it will miss it anyway because the reef R will "suck" most of the set (which will be big there) and leave the F area flat. That happens a lot in all surf spots, it's just that most surfers are not aware of this. When the WSL commentators do a proper "break breakdown" for Pipeline or Waimea, for example, these concepts appear also very clear.

NAM3km map at 2pm shows that today should be a calm day all day. Check the MC2km maps later to see if they foresee sea breezes.

It should be fairly sunny in fact, and that sure helps the thermal breezes.

Current wind map shows:
1-2) distant and close NW fetches that will end this small spell on Sunday
3) windswell fetch

1 comment:

(Ben) Jamin Jones said...

BTW There was a pretty cool water spout off Kihei yesterday afternoon 5:30 ish.