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      A Few Simple Rules   05/22/2017

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    • B.J. Porter

      Moderation Team Change   06/16/2017

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By the lee

Planing hulls

59 posts in this topic

yeh the second example has a crew standing well arft , definatly planning upwind.

/facepalm.

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IYO, is this boat planing?

 

http://www.youtube.com/watch?v=-_y8E0Wffkc

 

How about this one?

 

http://www.youtube.com/watch?v=OMlRhnC-YBI

 

I would say no & no, and I doubt the first one is hitting 18 knots in the video. When a boat going that fast has the helmsperson pump the tiller, generally the stern jumps around pretty hard.

 

And with less than 6 seconds of view of the stern waves of the boats in question, how exactly is anyone supposed to tell if the boats are planing? By the spray coming over the bow? By the really cool gybe in #2?

 

FB- Doug

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Know what other things have two wheels? Aeroplanes....

 

correlation between plane and plane?

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It's really simple to tell if a boat is planing. First, ask yourself if it's a J105. Then, substitute the answer to that in the second question: is the boat planing?

 

It goes like this:

Is that boat a J105? Yes

--------------------------- |

---------------------------\/

Is that boat planing? Yes

 

OR

 

Is that boat a J105? No

---------------------------|

---------------------------\/

Is that boat planing? No

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I think Kilo is a great buy at $35K. Fix the issues and you have a boat that will perform well anywhere. It's a shame the prod wasn't 2' longer but the hull form is excellent and more efficient in high speed downwind work than the FT

 

Hah! See ^^^^^^^^^^^^^ it is a planing hull!

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You are kidding, right?

 

Not even close. Neither of them. Not by a long shot.

Really? So the last one I posted (vid runs 1:48) is doing 18 knots in displacement mode?

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You are kidding, right?

 

Not even close. Neither of them. Not by a long shot.

Really? So the last one I posted (vid runs 1:48) is doing 18 knots in displacement mode?

 

I saw surfing, not planing.

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You are kidding, right?

 

Not even close. Neither of them. Not by a long shot.

Really? So the last one I posted (vid runs 1:48) is doing 18 knots in displacement mode?

 

I only watched 2 vids--now I see third one. You are moving right along there!

Definitely surfing.

But, what is your waterline length? 18 knots is well over "hull speed", but it isn't necessarily planing either--most of these larger fast monohulls aren't developing much in the way of dynamic lift. Exception being the really extreme ones. Compared to a dinghy they aren't lifting out of the water.

 

But, you are "planing" in that rather loose incorrect sense that sailors all use, as in, "My V15 planes upwind." Yeah, right;-)

 

PS looked up your boat.

Looks like about 30 ft waterline.

16 knots peak speed surfing is fast but not really planing. What was your average speed for 30 minutes? That will tell you more.

 

Your theoretical "hull speed" is 7.3 kts on 30'. Any moderate displacement sailboat can expect to exceed that--8.5 or 9 knots. Any more than that, and you are truly escaping, planing or no planing :-)

 

Another way to look at it is the length of the waves you are producing (assuming deep water!). 18 knot waves are 180 feet long. In other words you are very much past the ordinary displacement range. When your 30 footer is making 40 foot waves (8.5 knots) the stern is squatting and the boat is "falling" into the trough. The older more pointed stern shapes, at moderate displacement, ensured this would happen and there would be no escaping.

 

But in surfing conditions, even the old designs will hit absurdly high speeds. I've done just shy of 13 knots on the speedo in the open ocean (the GPS read about a half a knot higher) surfing a wave on a CCA boat with a 31 foot waterline.(42 overall). But in those conditions, even though we saw between 11 and 12 knots on most every wave, or once a minute or so, our 4 hour average over the bottom was exactly 9.0 knots (and not in the gulf stream or other heavy current).

 

So, what was your average speed?

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When your competitors can see the front of your keel going down wind, and your speedo isn't working any more because its out of the water.. Then your surfing. A speed boat that has lifted up out of the water is planing.

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fastyacht is right on- the orbital motions of steep waves will impart a major surge to the hull of a vessel and create a trim condition where the usual waterline length formula is meaningless, but the wave backsides will have a slowing effect as well, lowering mean speed. If a 30 foot LWL boat is doing 18kts in calm water, the discussion about planing becomes interesting. If doing so in 8 or 12 foot waves, not so much.

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fastyacht not my boat just plucked the vid as example.

 

most of these larger fast monohulls aren't developing much in the way of dynamic lift. Exception being the really extreme ones. Compared to a dinghy they aren't lifting out of the water.

 

But, you are "planing" in that rather loose incorrect sense that sailors all use, as in, "My V15 planes upwind." Yeah, right;-)

 

Ok so this Albacore ain't planing but it ain't surfing either so what does one call what it's doing 'cause, it ain't in displacement mode, amiright?

 

The older more pointed stern shapes, at moderate displacement, ensured this would happen and there would be no escaping.

So I probably should have tittled the thread "Is this a surfing hull", ie one that promotes sustained surfing.

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fastyacht not my boat just plucked the vid as example.

 

Ok so this Albacore ain't planing but it ain't surfing either so what does one call what it's doing 'cause, it ain't in displacement mode, amiright?

 

I don't know why you think that _isn't_ planing.. it certainly is.

 

Try these ones, possibly a bit more definitive:

 

even the lazy E in the second vid is planing.

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fastyacht not my boat just plucked the vid as example.

 

most of these larger fast monohulls aren't developing much in the way of dynamic lift. Exception being the really extreme ones. Compared to a dinghy they aren't lifting out of the water.

 

But, you are "planing" in that rather loose incorrect sense that sailors all use, as in, "My V15 planes upwind." Yeah, right;-)

 

Ok so this Albacore ain't planing but it ain't surfing either so what does one call what it's doing 'cause, it ain't in displacement mode, am I right?

 

The older more pointed stern shapes, at moderate displacement, ensured this would happen and there would be no escaping.

So I probably should have titled the thread "Is this a surfing hull", ie one that promotes sustained surfing.

 

 

As dinghy sailors, we would generally call that "planing" however it is in fact barely planing in the true technical sense. Well above hull speed, but not planed off.

15' wl "hull speed" 5.2 kt. That boat is doing what, 9 knots? The wave it is riding on is 45 feet long. She's pretty well "escaped" the trough. (Although I bet the water is only 10-15 feet deep--so the wave is more like 40 feet).

 

In this particular video, note that crew weight is amidships. If they moved aft, she might go a whole knot faster and actually lift out and plane. On heavier planing boats this is often needed top make it happen. Depending on hull shape it is needed on light ones, too. Put a crew weight of 350 lbs into V15 in 20 knots and sit in normal upwind position on a reach. Boat goes fast but lots of bow spray and wake. Now move the crew back, the boat literally jumps out of the water and truly planes, gaining a couple knots too. In both cases you'll be well above "hull speed" but you won't be planing in the 1st instance.

 

GP14 is another good example where this is necessary for planing. Move weight back, boat takes off. Weight fwd, boat plows a nice furrow in the water while going pretty fast, but not as fast as planing.

 

 

Unfortunately as sailors, we really haven't developed a vocabulary to handle the realities of post-hull speed sailing. If you have sailed a high performance trapeze dinghy, such as an FD, or a 505, you know how different the upwind "planing" is from planing on a reach. They aren't the same thing at all. That the boat gets over hull speed going to windward, and that you go at least 30% faster than you would if you tried to point as high as possible, doesn't mean it is actually "planing" and yet it isn't doing what a keelboat does, either. Or is it? Functionally, trying to get to the windward mark 1st, it really isn't any different. You can pinch any boat too close to the wind--sheet it in too far, sail it too high, and therefore go slower to windward. The difference is that for the FD, you are exceeding wave speed rather significantly. But boat isn't in that dynamically supported regime you experience on a reach, either. We just don't have words to describe this.

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Further complicating the issue is the weightiness of the boat. Light boats make a much less dramatic transition to the planing regime, as they don't have a pronounced resistance "hump" to climb. Best example of this is the 10 square meter canoe, the "IC". Next in line is the Dutchman, then the 505. Note that the latter is about 3 times heavier on its length than the canoe. In U.S. measure, the ratios are going from around 25 to 40 for the canoe (depending on skipper weight!) to around 70 for the 505. By the time you get to 100 (the threshhold of the "ULDB" ) you are into boats that have a pretty sharp hump. the GP14, Enterprise, Albacore etc are above 100. A lot happens from 80 to 120.

 

Units are: Displacement Long Tons

Divided by:

 

[(waterline length feet ) / 100 ] ^3

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... ...

 

As dinghy sailors, we would generally call that "planing" however it is in fact barely planing in the true technical sense. Well above hull speed, but not planed off.

15' wl "hull speed" 5.2 kt. That boat is doing what, 9 knots? The wave it is riding on is 45 feet long. She's pretty well "escaped" the trough. (Although I bet the water is only 10-15 feet deep--so the wave is more like 40 feet).

 

In this particular video, note that crew weight is amidships. If they moved aft, she might go a whole knot faster and actually lift out and plane... ...

 

Or they might drag the transom too much and slow down

 

I suggest dropping the term "hull speed" since it is almost meaningless. Instead, think of the relationship of speed-length ratio. This is the key to resistance, when you graph resistance against the spped-length ratio then you see the drag hump mentioned earlier... instead of talking about "climbing the bow wave" which is nonsense.

 

This is one reason why a good view of the WAKE of a vessel is one of the best ways to see the relationship between a hull that is supported by displacement and one that is supported by lift. In that video of Albacore #8147, the stern wave is relatively flat and crests well behind the transom... in other words, the "hole in the water" made by the hull is considerably longer than the hull itself, and the boat is no longer being supported 100% by displacement. What is the relative percentages of support due to displacement/lift? Dunno

 

The whole art of sailing is to balance developable power with the drag created by supporting & directing that power.

 

FB- Doug

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Most boats, especially keelboats, need to be sailed pretty close to dead flat to plane effectively. If you aren't flat and you aren't in a high-performance dinghy, you probably aren't planing.

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Know what other things have two wheels? Aeroplanes....

 

correlation between plane and plane?

Shit. I sure any hope any plane I'm on has at least three wheels. :o

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This topic can not be real

You've never planed, have you. Keep reading this thread so you'll know when you do.

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This topic can not be real

You've never planed, have you. Keep reading this thread so you'll know when you do.

 

#1 You have no idea who i am

#2 a Ben 10R will never plane

 

#3 watch this video of me driving

http://www.youtube.com/watch?v=C1kcUSaSSmo

#4 don't be an idiot

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This topic can not be real

You've never planed, have you. Keep reading this thread so you'll know when you do.

 

#5 Observe video #2 of my close friends and I on a fun delivery and wish you were there

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GP14 is another good example where this is necessary for planing. Move weight back, boat takes off. Weight fwd, boat plows a nice furrow in the water while going pretty fast, but not as fast as planing.

 

The GP 14 was designed for rough water, not high speed, and it's really too heavy to be considered a performance boat. Compared to other boats of the same time period, e.g. the Albacore and Jet 14, it will plane later and slower. On the other hand, it will be at least as fast, if not faster, when the wind is not quite strong enough to make the other boats break free.

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GP14 is another good example where this is necessary for planing. Move weight back, boat takes off. Weight fwd, boat plows a nice furrow in the water while going pretty fast, but not as fast as planing.

 

The GP 14 was designed for rough water, not high speed, and it's really too heavy to be considered a performance boat. Compared to other boats of the same time period, e.g. the Albacore and Jet 14, it will plane later and slower. On the other hand, it will be at least as fast, if not faster, when the wind is not quite strong enough to make the other boats break free.

 

Yes, of course. But that's the whole point really. Planing is easier to see happening when the boat is heavy and it jumps out of the water. The very light boats are more subtle and the issue of whether one is dynamically supported ("planing") or not is less certain. Taken to cats of course, until the past 20 years, cats were never designed to plane at all. Now, they are, more to prevent pitchpoling downwind. (Look at F18).

 

It is a "silly" topic but it is also not a silly one. It is an opportunity to look at how things work--and work differently--in different boats.

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surely this is planing??

 

Looks pretty slow to me. Look at the spacing between transverse wave crests. Looks to me to be around "hull speed".

 

And how on earth would you get that to plane, anyway? It is a (by modern standards) heavy (by old standards) light-moderate displacement cruising boat. D/(0.01L)^3 > 150. Hard to make a *dinghy* plane with that much weight. A boat this big has a tiny fraction of the sail carrying power of a dinghy. Planing? Never. Ever.

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This topic can not be real

You've never planed, have you. Keep reading this thread so you'll know when you do.

 

#1 You have no idea who i am

#2 a Ben 10R will never plane

 

#3 watch this video of me driving

http://www.youtube.com/watch?v=C1kcUSaSSmo

#4 don't be an idiot

 

That's flying. She looks pretty well behaved?

 

Numbers-wise, that J125 has almost perfectly identical ratios to the 505 (sail area to Volume^(2/3) and Displ/(0.01l^3) )--excepting of course the righting moment is proportionally less with 10 degrees heel so not as fast upwind relatively speaking as the dinghy. But downwind, you can expect it to get pretty close to the same Froude number as a 505.

 

And that Hobie looks great!

When they first appeared, my friends and I wanted to sail one so much. Never did get the chance.

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!st is surfing downwind with a bit of apparent wind and wave motion to help- 2nd is planing under true wind.

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It is a "silly" topic but it is also not a silly one. It is an opportunity to look at how things work--and work differently--in different boats.

 

And keep in mind that terms like "plane" and "surf" are man-made, and the technical-sounding definitions don't necessarily align with Mother Nature's way of doing things. I once read a definition that "planing" is when dynamic pressure supports more than 50% the weight. That's a pretty arbitrary dividing line. Also hard to determine by measurement, I should think.

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It is a "silly" topic but it is also not a silly one. It is an opportunity to look at how things work--and work differently--in different boats.

 

And keep in mind that terms like "plane" and "surf" are man-made, and the technical-sounding definitions don't necessarily align with Mother Nature's way of doing things. I once read a definition that "planing" is when dynamic pressure supports more than 50% the weight. That's a pretty arbitrary dividing line. Also hard to determine by measurement, I should think.

 

Yep. Multiple ways.

That one.

And the one where Fn > [take your pick of number]

And the one looking at CG rise.

And the old standby "chines dry" measure.

My favorite for powerboats is to look at where the resistance curve goes from steep, to a simple square (cubic power) rise. That's "over the hump" and the propeller matching is easy from there on.

 

It is a continuum. And it is different in different boat types. And lightweight sailboats are especially nebulous,

Obviously a bayliner is rather easy to figure out. Compared to an 18ft skiff, which just gradually goes faster and faster.

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get out in a dinghy, even a laser would suffice, in a good breeze and you will see what planing is. if you arent coordinated enough for a laser then find a friend with a performance dinghy (hell even a V15 will do the job if its windy enough...).

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This topic can not be real

You've never planed, have you. Keep reading this thread so you'll know when you do.

 

#1 You have no idea who i am

#2 a Ben 10R will never plane

 

#3 watch this video of me driving

http://www.youtube.com/watch?v=C1kcUSaSSmo

#4 don't be an idiot

 

That is most definitely not planing. For the simple reason that you are wearing a Gunners beanie. Anyone wearing a Gunners beanie, is incapable of making a sailboat plane, even a J-125. :P

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Sailed the 84 MORC Internationals in Erie PA on a Lindenberg 28. The distance race took us across the into an approaching cold front. After a long shallow beat we rounded a mark up behind long point and turned for Dunkirk, about 35 miles. Arrived two hours and fifteen minutes later. Total, non stop, spray to the spreaders planing the whole way.. One of the memories I hold dear.

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Sailed the 84 MORC Internationals in Erie PA on a Lindenberg 28. The distance race took us across the into an approaching cold front. After a long shallow beat we rounded a mark up behind long point and turned for Dunkirk, about 35 miles. Arrived two hours and fifteen minutes later. Total, non stop, spray to the spreaders planing the whole way.. One of the memories I hold dear.

I like that story! I hadn't heard anyone say "spray to the spreaders" in a long time.

Here's a Lindenberg 28:

http://www.svsoggypaws.com/fastlane/index.htm

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surely this is planing??

 

if the dinghy being towed isn't planing then that's a pretty good indication that the boat isn't. Not even close to surfing..,. and what's with that music? You can't possibly plane without listening to heavy metal.

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I don't know why you think that _isn't_ planing.. it certainly is..

I thought I did. See post # 16 above.

 

get out in a dinghy, even a laser would suffice, in a good breeze and you will see what planing is.

I have a Laser. Sometimes when sailing in a breeze it makes this humming noise.

I think this must be a by-product of planing.

Or not.

See above.

 

#1 You have no idea who i am #2 a Ben 10R will never plane #3 watch this video of me driving #4 don't be an idiot

#1 No, but I get this feeling you got an idea who you are.

 

#2 Right! Ben 10R is a sea anchor. Noted.

 

#3 Dude! Your awesomeness is sooooooooooo stratospherically off the charts! Please PM me a facsimile of your autograph right away so I can pin it up on the walls next to the images I cut out of my Sharon Green calenders from the '90's.

 

#4 Hey! Name calling is never useful you so and so.

 

Total, non stop, spray to the spreaders planing the whole way

Not so fast Mr. Fixit. Were there any waves?

See above.

 

And keep in mind that terms like "plane" and "surf" are man-made

Ah, semantics.

Where would this thread be without them?

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By the way the video I posted is something I found a while ago which really made me laugh…sarcasm people, sarcasm

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... ...

if the dinghy being towed isn't planing then that's a pretty good indication that the boat isn't. Not even close to surfing..,. and what's with that music? You can't possibly plane without listening to heavy metal.

 

^ this ^

 

blather about dynamic lift and wave-making etc etc is irrelevant if you're listening to lame music

 

FB- Doug

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This topic can not be real

You've never planed, have you. Keep reading this thread so you'll know when you do.

 

#1 You have no idea who i am

#2 a Ben 10R will never plane

 

#3 watch this video of me driving

http://www.youtube.com/watch?v=C1kcUSaSSmo

#4 don't be an idiot

 

That is most definitely not planing. For the simple reason that you are wearing a Gunners beanie. Anyone wearing a Gunners beanie, is incapable of making a sailboat plane, even a J-125. :P

 

Unfortunately this year you are probably right about the Gunners comment... :)

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This topic can not be real

You've never planed, have you. Keep reading this thread so you'll know when you do.

 

#1 You have no idea who i am

#2 a Ben 10R will never plane

 

#3 watch this video of me driving

http://www.youtube.com/watch?v=C1kcUSaSSmo

#4 don't be an idiot

 

That's flying. She looks pretty well behaved?

 

Numbers-wise, that J125 has almost perfectly identical ratios to the 505 (sail area to Volume^(2/3) and Displ/(0.01l^3) )--excepting of course the righting moment is proportionally less with 10 degrees heel so not as fast upwind relatively speaking as the dinghy. But downwind, you can expect it to get pretty close to the same Froude number as a 505.

 

And that Hobie looks great!

When they first appeared, my friends and I wanted to sail one so much. Never did get the chance.

 

Very well behaved until you crash ;) Seriously a fun boat and really lights up. Hit some 24's on Coastal Cup this year which was intense.

 

The Hobie 33 is an epic boat and is amazing in the big breeze.. hoping to do Coastal Cup on it in 2013.

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Sailed the 84 MORC Internationals in Erie PA on a Lindenberg 28. The distance race took us across the into an approaching cold front. After a long shallow beat we rounded a mark up behind long point and turned for Dunkirk, about 35 miles. Arrived two hours and fifteen minutes later. Total, non stop, spray to the spreaders planing the whole way.. One of the memories I hold dear.

Haven't thought about that race in years.Was that Creole Cookin you were sailing?

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Centerboard hum comes from detached flow over the board not because you are planing

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Centerboard hum comes from detached flow over the board not because you are planing

Actually it is caused by acoustic resonance matching the Karman vortex street frequency of the centerboard wake. You don't need to have a stalled board to get hum. In fact it is more likely when it is not loaded. But to your point yes, it is separation dynamics that cause it. A fat, rounded trailing edge is especially likely to create hum. The wider the edge, the lower the frequency. A sharp edge will prevent it, but only if the board is fair ahead of the sharpness. But also note that you are not likely to hear the effect unless the street frequency coincides with a structural vibrational resonance, typically of the board itself or quite frequently of a piece of poorly stiffened structure adjacent to the centerboard trunk. I haven't actually worked on solving the laser problem specifically, but having heard that laser hum many times, I suspect it is not the board that is humming (although it transmits the vibration) but rather some part of the hull/deck nearby.

 

The Thistle is also known to experience this, but with the rudder. If you look through the 1992 or 1993 issues of the Bagpipe, you'll find an article on it complete with wind tunnel tests demonstrating the vortex street very clearly.

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A fat, rounded trailing edge is especially likely to create hum. The wider the edge, the lower the frequency. A sharp edge will prevent it, but only if the board is fair ahead of the sharpness. .

How about a squared off trailing edge. Say 1/8 wide or possibly less?

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A fat, rounded trailing edge is especially likely to create hum. The wider the edge, the lower the frequency. A sharp edge will prevent it, but only if the board is fair ahead of the sharpness. .

How about a squared off trailing edge. Say 1/8 wide or possibly less?

 

See here for a pretty thorough discussion on foil hum including some cool videos and input from the all knowing christian: http://forums.sailinganarchy.com/index.php?showtopic=123479

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Really interesting discussion! As a guy who grew up in a thistle and knows that 'hum' well I've been wondering this with my new boat. It's an 11 meter OD, not really made for ocean where I keep her. According to these formulas our ULDB number is 81, hull speed around 6.8.

 

What's striking me here is that I'm learning to drive on the ocean, and its VERY fucking different. You sure as hell know when youre surfing (down a wave that is), but that sustained 11 knots downwind has been hard to discuss. Apparently this boat is known for planing uneventfully (maybe the only thing it does uneventfully), and its good to heard y'all's take on this re keelboats.

 

We're playing with weight distribution as above and you really do have to watch your speedo. Sometimes I'm tempted to turn damping way up for downwind...

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Sailed the 84 MORC Internationals in Erie PA on a Lindenberg 28. The distance race took us across the into an approaching cold front. After a long shallow beat we rounded a mark up behind long point and turned for Dunkirk, about 35 miles. Arrived two hours and fifteen minutes later. Total, non stop, spray to the spreaders planing the whole way.. One of the memories I hold dear.

Haven't thought about that race in years.Was that Creole Cookin you were sailing?

Creole Cooking,, that's the girl, what were you on? A local J-29 won overall that year I believe.

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Sailed the 84 MORC Internationals in Erie PA on a Lindenberg 28. The distance race took us across the into an approaching cold front. After a long shallow beat we rounded a mark up behind long point and turned for Dunkirk, about 35 miles. Arrived two hours and fifteen minutes later. Total, non stop, spray to the spreaders planing the whole way.. One of the memories I hold dear.

Haven't thought about that race in years.Was that Creole Cookin you were sailing?

Creole Cooking,, that's the girl, what were you on? A local J-29 won overall that year I believe.

I believe the factory J27 won it overall sailed by Charlie Scott.I sailed on my dads Kirby 30 Gotcha.We pulled the halyard box out of the mast about 5 miles after rounding Dunkirk and had to retire.Nothing like motoring into heavy seas on a 30 ft.boat with a 6hp.outboard back to Erie.

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Sailed the 84 MORC Internationals in Erie PA on a Lindenberg 28. The distance race took us across the into an approaching cold front. After a long shallow beat we rounded a mark up behind long point and turned for Dunkirk, about 35 miles. Arrived two hours and fifteen minutes later. Total, non stop, spray to the spreaders planing the whole way.. One of the memories I hold dear.

Haven't thought about that race in years.Was that Creole Cookin you were sailing?

Creole Cooking,, that's the girl, what were you on? A local J-29 won overall that year I believe.

I believe the factory J27 won it overall sailed by Charlie Scott.I sailed on my dads Kirby 30 Gotcha.We pulled the halyard box out of the mast about 5 miles after rounding Dunkirk and had to retire.Nothing like motoring into heavy seas on a 30 ft.boat with a 6hp.outboard back to Erie.

That's right,,, Smiles.. The original J-24 'Ragtime' was there also.

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A fat, rounded trailing edge is especially likely to create hum. The wider the edge, the lower the frequency. A sharp edge will prevent it, but only if the board is fair ahead of the sharpness. .

How about a squared off trailing edge. Say 1/8 wide or possibly less?

 

It is better to square at off-square to cause vortices to prefer one edge rather than the other. You can tune the width if you know what frequency you are trying to avoid.

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