thrusters, what do they really do ?

[surfalex]

I had several explanations, some makes more sense then others.
What good do they really do ? I sail in the Gorge

[dllee]

Depends who's and what setup you're talking about.
RealWinds small side fins help a little, allow a pivot point for carving.
Big sides with small trailer's would pivot around the outside fins like a twin fin, and the small trailer keeps in in line.
Equal size would mean 3 fins with more area than one single fin, a compromise of all worlds.
But you can't talk fins without factoring in shape, width, widepoint, rocker, and bottom shape.

[U2U2U2]

Thrusters.. From the surf world are 3 fins of equal size, or near the same.

The windsurf adaptation is normally a 2+1 fin set up, so 20cm center and sides of 10cm...as a for instance.
The windsurf community have referred to anything with 3 fins as thrusters, Tri fins, 2+1, single thruster...

It's like the difference between a roadster and a convertible car.

Since multi fins have re gained a new popularity since around 2007, the debate of their usefulness has as well. The fact that most companies now have Tri finned boards in the selection , esp now FSW, that they have tested and found them useful, or a marketing gimmick that sounds like you need them. You didn't ask about quads or 5 fin box boards, that offer other fin configurations.

The opinions that I have followed : and since you don't ask for a comparison with singles.
Tri fins , do have more area than a comparable single, this is needed to compensate for the shorter center fin, this additional area increases drag, which in turn causes slower planing and top speed is reduced.
Conclusion on those, if 'you have the need for speed' those boards don't come with a 3 fin option. If early planing over all other considerations is critical then again it ain't a 3 finned board.

NB : both those can be narrowed by fin selection, the board itself when made can be improved by fin placement, toe in, of course the rails and bottom shape, length width...more...
Optimize fins can be done irregardless .

The positive aspects of a Tri fin: starting in shallow water, or sailing in, cause the fins are shorter. The board because of the fins being spread out , contact in different areas, will be more planted, more secure feeling in choppy water.
Turns because the pivot point is not centered on 1 long fin, is snappy in comparison, the feel will generally be like a smaller board, the rail shape and amount of foot pressure will effect this.

The Tri fin will go upwind easier and to some degree better, the fins have more area that allow that.

It's possible to change the overall feel of the board, it's character is going to remain, but the characteristics can be tweaked, if 3 fins of equal or near equal size as used the feel with be much like a twin, skaty, loose. The 2+1 setup will feel much like a single, with yet some of the 3finned traits.
Going larger or small and forward or aft, if able , will further expand the feel.

The gorge IMO is a prime spot for multi fins, 3 or 4, twins have lost favor, but have some plus, speed being one.

[U2U2U2]

These 4 all have three fins, they all feel different.

[isobars]

I've had many boards with single fins and with central fin plus two or four much smaller thrusters. My preferred sailing style in the Gorge includes extremely tight and powerful slashing at full speed, landing jumps while pointed in whatever direction *I* choose (rather than just off the wind), pointing very high (for a wave board) speed, and jibing very tight and fast any damned place I choose without worrying about chop ... all while powered very strongly (overpowered, everyone tells me). Thrusters helped me learn all that, but as my skills have improved I find them less important. I'd have to guess they meant the difference between precise control and slippy slidin' in those pursuits maybe 50% of the time decades ago, more like 2 or 3% now.

Until, that is, I really, truly AM overpowered. Then thrusters add significantly more precision to my moves and, ultimately in the biggest gusts, the confidence to slash and bash in what would otherwise be survival sailing. How MUCH they help varies more with board shape than fin count and power level. i.e., I see more difference in tracking between different boards than between thrusters vs no thrusters.

Thrusters do let me run much smaller central fins, so the total drag is not noticeably different.

I once compared 5 or 6 Gorge high-wind boards head to head on an insane day at the Hatchery decades ago. Despite their all having one central fin (all but one also had 2 or 4 thrusters), one model completely, totally, absolutely blew every other board in that test completely off the river ... and I didn't even try it until I had put in well over 8 hours of testing in full nuke wind ... at least 2.8 for big guys ... on a 3.2. There weren't more than a couple of sailors left by then and I was tired as hell, but that board was SO superior it provided by FAR my best session of the day despite yet another big surge in wind speed from 6 'til after sunset.

My point: hull design can trump fin count. My slashiest board at present has only one fin, and it (or my skills) fails me only once or twice on a normal windy day ... maybe a bit more often in really gusty conditions.

Rent, demo, borrow, or buy one at a swap meet (cheaper and much more convenient than renting or demoing). Push yourself and the board HARD next windy day. TRY to spin it out. Sail it VASTLY overpowered (efficient sailors who use smaller sails than their peers don't need thrusters). If you find a big performance improvement, you win ... whether it's the thrusters or the hull shape. There were several excellent thrustered boards for double digit prices at Sunday's swap meet.

Mike \m/

[U2U2U2]

Rather than compare, what occurred decades ago .. Wonderful that ..

Have a look at the AWT riders at Punto San Carlos, OR THE PWA events with some names like Fernandez, Koster,Mussolini, Traversa, who won the RedBull Storm chase...which doesn't go to the edges of the Earth unless the wind is
Freekin ...insert favorite phrase .. Nuke, blasting, really wound up..
Who are all on multi finned boards,

To quote above post.. ..efficient sailors who use smaller sails than their peers don't need thrusters ...


The year is 2016.. Please join us.

[jingebritsen]

got jagged, fast moving waves? buckets of wind power? maybe multifins are for you.

low slope, crumbly waves that break far slower? need tons of upwind power in lighter winds? maybe single fins are right.

consistently, in florida conditions those folks that try to use high wind venue boards and sails in surf, mope about and sit on the beach most. mainly because the times they do go out, their equipment and skills don't match the conditions.