Ef­fi­cient Pump­ing

There’s more to pump­ing than just pulling in the sail.

Sailing World - - From The Experts -

Q A few years ago, I was work­ing with two Melges 20 teams in prepa­ra­tion for an up­com­ing world cham­pi­onship. Both had world-class sailors aboard and per­formed quite well, but when it came to down­wind pump­ing tech­nique, there were dra­matic dif­fer­ences. Gen­er­ally speak­ing, one team worked mostly with large, pow­er­ful pumps while the other fo­cused on smaller, short­stroke move­ments. Some­times one tech­nique worked bet­ter; other times it didn’t. So, we set out to quan­tify the dif­fer­ence in per­for­mance to get a bet­ter sense for which tech­nique was most ef­fec­tive in var­i­ous con­di­tions.

Our boats were in­stru­mented, and we had data feeds com­ing off each boat, so we could plot VMG. I also had a pro­gram called Dart­fish, which among other things, could plot move­ment at the end of the boom, mak­ing it clear what type of pump­ing was be­ing used. Track­ing the end of the boom through the var­i­ous pump­ing meth­ods re­veals just how dy­namic these move­ments are. Im­pulse pumps pro­duce pretty straight tracks, with the boom mov­ing pretty hor­i­zon­tally. Row­ing pumps, and some­times re­verse pump­ing, cre­ated tracks that were quite el­lip­ti­cal. The el­lipses could even be di­ag­o­nal, in­di­cat­ing the pumps were pulling down as well as in. We started plot­ting those data num­bers on a graph and com­pared that to ac­cel­er­a­tion over cer­tain pe­ri­ods, and we started to see a pat­tern that suggested where each type of pump worked best.

Row­ing Stroke

This is what usu­ally first comes to mind in any dis­cus­sion of pump­ing. You lean for­ward, us­ing your back, leg mus­cles and up­per body, and ag­gres­sively pull on the sheet, much like a row­ing stroke. It im­parts a huge amount of en­ergy into the boat, and it’s what you see when a bird starts to take off. It’s not mak­ing lit­tle strokes; it’s do­ing the big, long, quick strokes to pro­duce max­i­mum lift. This type of stroke is great in light­weight keel­boats and dinghies, when you’re in mar­ginal con­di­tions, right on the edge of catch­ing waves, and you need that big im­pulse of en­ergy to get your boat ac­cel­er­at­ing onto the wave and be­ing able to start glid­ing in surf­ing mode us­ing the down­hill side of it. It’s a rel­a­tively quick pump, but it’s got a huge amount of force.

We dis­cov­ered that row­ing the boat onto a wave with this stroke was a pretty good tech­nique in mar­ginal plan­ing and surf­ing con­di­tions, un­til you got “on the step,” mean­ing you’ve started plan­ing down the wave, and the ap­par­ent wind has in­creased and shifted for­ward. The prob­lem with a row­ing pump, once on the step, may have to do with the fact that your steer­ing an­gle is now much nar­rower, so when you do the big eases and trims, you’re stalling the sail at ei­ther end of the pump­ing range — the sail is no longer trimmed per­fectly. The row­ing pump also has the same ef­fect as mov­ing the crew weight. That roll, usu­ally from zero to 7 de­grees, can kill flow

on the foils. Once on the step, it’s all about ef­fi­ciency; you lose if you try to put too much en­ergy into it.

With heav­ier- dis­place­ment boats, the re­turns on the row­ing stroke di­min­ish rather quickly as the boat gets big­ger and heav­ier. With a pro crew and linked winches, you can prob­a­bly make it work, but oth­er­wise, it will only stall the sails.

Im­pulse Pump

Now you’re surf­ing down the wave, but sooner or later, you start de­cel­er­at­ing. It’s like the wave is ac­cel­er­at­ing com­pared to your speed, but in re­al­ity, you’re just slow­ing down. This is the time to give a short, snappy pump — one that gives just enough im­pulse to flick the main­sail and asym­met­ric spin­naker leech, im­part­ing enough en­ergy to reac­cel­er­ate and con­tinue rid­ing down the wave. Re­turn­ing to my bird anal­ogy, once it’s fly­ing, it just needs small, tip- of- the- wing move­ments to keep it go­ing. When we’re us­ing the im­pulse pump, we al­ready have a lot of ki­netic en­ergy go­ing be­cause we’re plan­ing; all we’re try­ing to do is match that speed.

If the boat gets re­ally loaded up, the short, quick im­pulse pumps will keep the boat go­ing. The boat is quite del­i­cate in the plan­ing mode, so re­sist the urge to give it a big pump. Once the boat is plan­ing, stick with im­pulse pump­ing. This type of pump will work on heav­ier boats, even with sym­met­ric spin­nakers, once on a plane. For the spin­naker, just make sure the guy and sheet are pumped si­mul­ta­ne­ously.

Re­verse Pump

We al­ways think of pump­ing as pulling, but the most im­por­tant tech­nique is ac­tu­ally the re­verse pump. The idea is to let the sheet go out just a lit­tle bit — gen­er­ally sev­eral inches or so — and then quickly catch it, or stop it. That re­flexes the en­tire sail open and then re­flexes it closed again. It’s the recharge pump that gets the flow back on the sail, so both the row­ing pump and im­pulse pump­ing are closely con­nected to the re­verse pump. Watch some re­ally good sin­gle­handed, dinghy or keel­boat sailors, and you’ll see them flip their hands open; the sheet goes out, and then they stop it hard. They don’t pump; they just stop the mo­tion. The whole sail opens up, re­gain­ing flow, and then closes again.

Sup­pose you have a gust com­ing on. You’re al­ready plan­ing, but you’re not go­ing to deal with the gust by eas­ing the sail out so that it’s rag­ging. So, you do a quick re­verse pump as it hits, briefly re­leas­ing the leech, which gets rid of a lit­tle helm. You can usu­ally feel that change. Then the leech snaps back in nat­u­rally. Or, it may be that you’re just try­ing to get over a wave. The boat gets loaded up for a few sec­onds, and that’s when you give it a lit­tle re­verse pump. It’s an ex­cel­lent tech­nique for when there isn’t enough weight in the main­sheet to do a tra­di­tional pump.

The re­verse pump is strong in all con­di­tions. We use it a lot on asym­met­ric- spin­naker boats now be­cause, with the wind­ward-lee­ward cour­ses, it’s all about VMG — how low we can go, not how fast we can go. On a TP52, even in plan­ing and surf­ing con­di­tions, the asym­met­ric trim­mers will some­times give the sails a lit­tle ease and then a hard stop. The sail is trimmed cor­rectly, and then they just go out from there. It might pro­duce a lit­tle curl. The same with the main­sail trim­mers, and when it’s done to­gether, the boat reloads, as it al­lows you to pump again. The re­verse pump works well on heav­ier, sym­met­ric- spin­naker boats too.

Un­less we’re in very strong con­di­tions, it’s dif­fi­cult to jump to the next set of waves, so no longer do we sail straight cour­ses. Mod­ern boats sail down­wind through as much as 80 de­grees. They’re ap­par­en­twind ma­chines, and we can use the three pump­ing modes to sail quite dif­fer­ent cour­ses. When we catch a wave, we can go re­ally low, us­ing im­pulse pumps and re­verse pumps to keep it go­ing. Then, at the bot­tom of turn, crew weight moves to lee­ward, even on keel­boats, to help the boat turn back up. We reload the up­turn as the ap­par­ent wind moves aft, and put more force in the sails, then, with a big row­ing pump, off we go again.

Com­bine the above with steer­ing tech­niques largely de­rived from the 49er and 470, and down­wind trim be­comes dy­namic to the point where up­wind sail­ing is no longer the most phys­i­cal part of the race — that’s now the down­wind legs. Even big­ger, asym­met­ric keel­boats are be­gin­ning to be sailed like dinghies, shift­ing weight around to help steer in ad­di­tion to con­stantly shift­ing from one pump­ing mode to an­other, work­ing to pro­mote and main­tain a plane. It’s fast, so get pump­ing. Q

Mod­ern boats sail down­wind through as much as 80 de­grees. They’re ap­par­ent-wind ma­chines, and we can use the three pump­ing modes to sail quite dif­fer­ent cour­ses.

PHOTO : PAUL TODD / OUTSIDEIMAGES . COM

A co­or­di­nated pump of the sheets will quickly trans­fer en­ergy into the sail plan, but dif­fer­ent pumps work best for cer­tain con­di­tions.

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