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Old 28-12-2017, 06:36   #196
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Re: What is "Hull Speed" Anyway

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Well, our bow looks like this too, with the hard chine beginning well forward of the mast. It's not as pronounced as 'Safran', but it's there. Anyway, even the chine just turns green water into a wall of heavy spray, which still sucks to be under when you're up forward.

It's still wetter than other boats we've sailed. Even the most modern race boats have foredecks that are seriously wet. If you look at videos of IMOCA boats now, they're tossing at least as much water back over the deck as did older designs.

I think that the move toward a fuller entry helps, but I think that it's pretty hard to say that any of the fine plumb bows are submerging less than more traditional designs with rake and flare.

But, who cares?? I'm perfectly happy to see the bow punching through seas--from under the dodger in the cockpit! I don't really care if we're putting a ton of water down the deck.

We just slow down when it's time to do some foredeck work. We're cruising, so if we're slowing down for a while to make the bow crew (usually me) happy, so be it. I'll take that over hobby-horsing my way along for days!
Did you ever have problems from the nav lights getting submerged?

I think as with so many things preference regarding bow type may be influenced by where you sail. I would be loathe to have an even wetter foredeck than I already have. Although I now recognize how extra buoyancy at the bow works against performance.

Incidentally I, as a rule, heave to to do foredeck work in anything above F5. That might be a beneficial tactic on your boat. Getting washed overboard could ruin your whole day . Also I just hate being doused with cold water., sometimes 3 or 4 degrees up here in winter.
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Old 28-12-2017, 07:08   #197
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Re: What is "Hull Speed" Anyway

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Did you ever have problems from the nav lights getting submerged?

I think as with so many things preference regarding bow type may be influenced by where you sail. I would be loathe to have an even wetter foredeck than I already have. Although I now recognize how extra buoyancy at the bow works against performance.

Incidentally I, as a rule, heave to to do foredeck work in anything above F5. That might be a beneficial tactic on your boat. Getting washed overboard could ruin your whole day . Also I just hate being doused with cold water., sometimes 3 or 4 degrees up here in winter.
The lights are pretty much at the top of the pulpit, but I have not seen them go under. I did on my heavier boats, though. It's sort of counterintuitive, but I think that raked,flared bows can be wetter in some conditions. The boat starts to hobby-horse, building more and more pitching moment, until she finally dunks under pretty well-also slowing the boat down by a lot. We don't really see that.

Usually, our 'bow under water' moments involve punching through a sea, with up to about a foot of water sluicing down the deck in the worst cases. We get quite a river washing across the winches at the back of the cockpit. But, we stay dry. Even when hand steering it's pretty pleasant.

I think that the very heavy flare to the hull keeps the bow from going too far under in our case. I also think that not starting the flare until further aft is the way to go. You get the benefit of added buoyancy, but it's far enough back that it doesn't seem to put the brakes on the way a more flared bow does.

For us, we don't really need to heave to. We either pinch right up, essentially stopping the boat, or bear off nearly ddw. Either way makes things fine to deal with in any weather we've sailed in so far. Heck, we even do the pinching maneuver for someone to do their business on the head. It's just so much more pleasant to not be slapping around at a 25 degree angle when taking your morning constitutional.

Heaving to for us involves a little more than just a turn of the wheel (runners and water ballast sometimes), so just stopping the boat or going ddw is better.

In any case, we typically stay off the foredeck when things are wet up there. It's nothing to just 'park' for a minute and do what we need to do.
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Old 28-12-2017, 09:40   #198
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Re: What is "Hull Speed" Anyway

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Did you ever have problems from the nav lights getting submerged?

I think as with so many things preference regarding bow type may be influenced by where you sail. I would be loathe to have an even wetter foredeck than I already have. Although I now recognize how extra buoyancy at the bow works against performance.

Incidentally I, as a rule, heave to to do foredeck work in anything above F5. That might be a beneficial tactic on your boat. Getting washed overboard could ruin your whole day . Also I just hate being doused with cold water., sometimes 3 or 4 degrees up here in winter.
A drysuit will solve this issue. I purchased an Ocean Rodeo Ingnite drysuit for the conditions you’ve described.
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Old 28-12-2017, 10:11   #199
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Re: What is "Hull Speed" Anyway

Shut it down. It's beating a dead horse.
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Old 28-12-2017, 11:00   #200
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Re: What is "Hull Speed" Anyway

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Did you ever have problems from the nav lights getting submerged?
...
I think that happens with really bad conditions no matter what the boat, being obviously bigger a problem on a smaller boat.

A decade ago on a 36ft boat I had exhilarating sailing conditions passing St Vincent cape at night, well exhilarating because I was sailing solo and my wife was not there to complain about LOL.

I was sailing fast with maybe 25 to 35K winds and 6 meter waves on a night with a full moon, obscured from time to time by dark clouds.

It was great fun and I remember looking at the sometimes submerged lights at the bow and at the colored water. Nice show, till one of them went off.

No way I was going there to replace a light on those conditions, alone at night. That is a zone with high ship and fishing traffic and I was far away from the coast (to avoid fishing nets and buoys) near the shipping lane.

It was no fun anymore, even if sailing I put my engine light on and become worried. I now have two light systems to avoid any problem, one near the water and another on top of the mast.

And by the way, the boat had not a plumb bow. Mine now, even if not completely plumb, is close to that but due to the diference of sizes (36 to 41ft) it is less wet than the 36ft...except when it goes faster against the wind.

I don't believe you can go fast against the wind and big waves without getting wet, even on a 60fter. If you are not getting wet then you are not having fun and you are going too slowly LOL.
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Old 28-12-2017, 11:07   #201
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Re: What is "Hull Speed" Anyway

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A drysuit will solve this issue. I purchased an Ocean Rodeo Ingnite drysuit for the conditions you’ve described.
You don't need a dry suit that makes you sweat. An offshore sailing suit and proper waterproof shoes or boots will do the trick. Look at the guys on the Volvo, they are surely getting wet but they are not wearing dry suits (rubber).

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Old 28-12-2017, 11:51   #202
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Re: What is "Hull Speed" Anyway

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You don't need a dry suit that makes you sweat. An offshore sailing suit and proper waterproof shoes or boots will do the trick. Look at the guys on the Volvo, they are surely getting wet but they are not wearing dry suits (rubber).
Actually Polux, the volvo guys do in fact quite often wear drysuits - but breathable ones usually - like this here:

HPX GORE-TEX OCEAN DRYSUIT

I had one of those on board and one of these: https://www.kayakacademy.com/collect...nt=15911323206

multi-race Volvo guys in fact recommended both options to me.

They were both brilliant - much much better than a typical sailing foul wear gear in several regards - you NEVER get wet at all inside, and they provide excellent flotation and warmth in the water, and they are fast and easy (with the front zip) to get in and put of. They have integrated socks - so you can wear anything you want on your feet. The second one you can get with a custom fitting which is quite nice.

On the thread topic - what are you guys still debating (other than the actual dimensions of Docks boat lol)?

As to the question about passage speed - about a decade ago I took a whole big collection of passage data (I only used data that I could vet and trust) from about 300 boats and did a regression and got a pretty good fit with this formula:
(average speed in kts) = 2.62 + 0.066*SA/D ratio + 0.051*LWL in feet

Yes, I know theory says that the lwl should be sqrt, but I tried that and it did not fit the actual real world data better than the above. Now boats have evolved a bit - and things like canting keels and water ballast would probably change the above but short of things like that, this formula gets you within 10% of actual results most of the time.

edit: TJ - the 'high performance' end of the boat in this sample were boats like Jim C's Heart of Gold. Yours would be a bit out of/beyond the distribution I modeled.
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Old 28-12-2017, 12:11   #203
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Re: What is "Hull Speed" Anyway

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On the thread topic - what are you guys still debating (other than the actual dimensions of Docks boat lol)?
I think the debate's long over-We're just a bunch of guys with too many holiday hours on our hands.

What better way to kill some time than to bicker about boat design?? And, to cyber-measure Dock's boat, of course.

I plugged in your formula. I'd say that it's probably within 10% of our long term average. I don't drill down too hard into our performance, but I don't think that we're quite averaging 200/day, probably 180-190 sailing doublehanded. Your formula gave 7.3 for us, so it's pretty good for real world cruising speed, I reckon.

We sail like a couple of slackers, though. We could probably do a lot better if we had the desire to do so.
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Old 28-12-2017, 12:14   #204
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Re: What is "Hull Speed" Anyway

not sure - did you use the sa/dpl ratio =

SA÷(D/64) ^ 2/3


The article had this footnote in it re the ratios (sorry the forum messes up the formatting):

Table 2. Calculation and range of performance ratios
Ratio
Formula
Range
Displacement to Length
(DLR)
(D/2,240)÷(0.01xLWL)3
From about 50 (very light) to above 450 (very heavy) for the boat’s length
Sail Area to Displacement (SA/D)
SA÷(D/64) 2/3
From about 12 (little sail area) to about 35 (lots of sail area) for the boat’s displacement
D = Displacement in pounds
LWL = Length at the waterline in feet
SA = Working sail area, defined as total area of main and mizzen (including roach) plus area of foretriangle (ignoring any jib overlap), in square feet
The displacement to length ratio (DLR) is a non-dimensional number that measures wave-making drag by quantifying how many long tons of water the boat displaces for each foot of waterline length. A high value means that the boat must move a great deal of water out of its way for its length, and its speed will be constrained by that length. Low DLRs means low wave-making drag, which means that in the right conditions the boat can surf. High DLRs correspond to comfort and load-carrying ability and low DLRs to speed.
The SA/D ratio is a non-dimensional number that roughly corresponds to the power-to-weight ratio for a car. It quantifies how much sail area the boat has for each cubic foot of water the boat displaces. A high ratio means the boat will perform well, particularly in moderate to heavy wind conditions where friction is less important than wave-making drag in determining speed. High SA/D ratios correspond to agile, responsive boats under sail, and low SA/D ratios, particularly below 15, mean sluggish, under-canvassed boats.

edit - hmmm - it does look like it is calculating low to me - I wonder if I have pulled the wrong coefficients. can't double check right now, but will later.
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Old 28-12-2017, 12:23   #205
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Re: What is "Hull Speed" Anyway

Evans, I got it. My stupid little screen made the + signs look like division signs. Maybe I need to finally accept getting older and get some reading glasses...
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Old 28-12-2017, 12:29   #206
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Re: What is "Hull Speed" Anyway

^^ ok, and I would expect both you as sailors and your boat design to be above this curve . . . . . but I still wonder if I pulled the last/best coefficients as they look lower for Hawk than I remember.

a huge variable among the cruising fleet is how much motoring you do in light airs. I know dashew drove their averages way up by motoring pretty much anytime the sailing speed dropped below 8kts; whereas we pretty much only motored if we were stopped and slamming the sails.
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Old 28-12-2017, 12:39   #207
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Re: What is "Hull Speed" Anyway

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^^ ok, and I would expect both you as sailors and your boat design to be above this curve . . . . . but I still wonder if I pulled the last/best coefficients as they look lower for Hawk than I remember.

a huge variable among the cruising fleet is how much motoring you do in light airs. I know dashew drove their averages way up by motoring pretty much anytime the sailing speed dropped below 8kts; whereas we pretty much only motored if we were stopped and slamming the sails.
We're generally content to go relatively slowly. Like you, it's really down to whether or not the sails are staying full. I won't let my sails suffer the abuse of light-air slatting. I drop everything and start the engine once I start seeing it.

It's possible that we're at 200/day average. We've certainly had passages well over 200/day. I really don't know for sure. We just recently got a plotter that does averages, and our Charleston-Ireland trip was 3700 miles, averaging 8.0-192/day. There was quite a bit of light stuff early in that trip, so we do better in the trades.

I just looked up 2017-we sailed a mere 1630 miles this year, average speed was 7.8. This was from UK to the Med over the summer-lots of light stuff.

As an aside, we are generally very conservative on our sail plan while I'm off watch. Jenny's a long way from being an adrenaline junkie (we are sailing our home), so typically before I go off watch, we'll mellow out on the sail plan a little bit. Real world, this probably costs us 10-20 miles a day. I don't mind a bit. She's been with me at this for over a decade, and keeping her content far outweighs any performance considerations.
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Old 28-12-2017, 12:53   #208
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Re: What is "Hull Speed" Anyway

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You don't need a dry suit that makes you sweat. An offshore sailing suit and proper waterproof shoes or boots will do the trick. Look at the guys on the Volvo, they are surely getting wet but they are not wearing dry suits (rubber).
The best of both worlds. I'll do a review on it as soon as the pond ice thaws, it's -11 degrees F today. We also have some Gill offshore jackets and bibs, but this suit has the added advantage of doubling up as a survival suit. If you find yourself in extreme weather.... the Ocean Rodeo Ignite is what you wanna be wearing.
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Old 28-12-2017, 20:47   #209
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Re: What is "Hull Speed" Anyway

Wow TJ, I just checked your boat details on your blog, that is a seriously impressive bit of kit!
I have met the designer Paul many times over the years, hes a great guy.
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Old 28-12-2017, 23:21   #210
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Re: What is "Hull Speed" Anyway

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Wow TJ, I just checked your boat details on your blog, that is a seriously impressive bit of kit!
I have met the designer Paul many times over the years, hes a great guy.
Lol.. When I first looked at his blog I also went wow, I've seen a couple of others react the same way.
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