Hull/Speed dynamics of Camano/Helmsman

[Nomad Willy]

Eric, what you say about the speeds is generally true, but not true of the Camano. Per Helmsman, who now builds them.

The hull-form is somewhat unique, called "keel form" hull. The design significantly reduces the bow wave one needs to climb over in the speeds just over hull speed. It produces a smooth fuel efficiency curve up to 15. But the hull form becomes unstable above 15. Hence, Helmsman will power them to approach but not exceed 15. Per Helmsman. And you can run them at the speeds you like up to 15 without paying the penalty of "the wall" effect normally between hull speed and planing speed.

There is an old Camano promo film on YouTube that discusses it.

 

[Nomad Willy]

I was talking about what speeds the hull was designed to run at. Being a planing hull with the required power the 31 Camano should be capable of cruising at 25 or more knots. But of course if you put too much weight onboard she’ll fall short.

What percent of power would you need to run continuously at 12 knots? And are you overloaded?

And an important element of this is how the designers and builders decided on what power to install in the boat. Knowing they had a planing hull in a trawler marketplace I would submit that they would be heavily inclined to underpower the boat .. at least to some degree. That would be an overpowered trawler (where it works nicely) or an underpowered Cruiser .. where it would not.
No boat operates continuously “on the hump” so it’s not surprising that Camano owners don’t cruise at 11-12 knots. You’d be better off w a longer hull for that speed.

But the boat (as a whole) is wonderful. At one point .. probably 14 years ago or so I was in a mindset to own a Camano myself. Was looking at them. But one of the significant reasons I bought my Willard 30 was that it didn’t have a FB. A pervious owner thoughtfully removed it. But most people like the FB.


FWT wrote the #1 post above post but rather than continue the hijack I took the liberty of starting a new thread w FWT’s follow-up on my post re Frank’s thread on cruising the Salish sea near Campbell River.

To read this ideally one should read #2 post and then #1.

 

[Nomad Willy]

Yes the Keel-Form hull goes way back. Atkin designed several keel-form hulled boats. The’ve always been sort of a hybrid design. Box Keel is their name and most or all of them could (legitimately or not) be called a semi-displacement (SD) hull. The part (box keel or the rest of the hull) that is primary in hull classification is probably not well established. My own opinion is that the “box” is (generally speaking) an addition to an existing hull-form that is Planing or SD in nature.

But SD would require some element or elements of the hull that would disqualify it as a planing hull like a buttock line not straight but w some angle. I think that the aft sections of the Camano/Helmsman (CH hull) running to the bottom of the transom horizontally, level and straight would be pure planing elements of a planing hull.
Also we know the CH hulled boat is capable of speeds far above displacement speed also strongly indicates the CH boats are probably planing hulls.

The Box Keel itself on the CH is very small .. as in not a big percentage of the hull below the WL. I view it as a special purpose keel. Most or all box-keel boats I’m familiar w are considerably larger and incorporate hull shape elements of SD hulls .. like rocker. IMO one pretty much needs rocker for a good SD hull.

So as far as classification goes I see the CH as modified planing hull or a planing hull w a SD feature .. that being the box keel.

FWT wrote;
“But the hull form becomes unstable above 15” .. knots as the sentence went.
Could you elaborate on the unstable nature of this design? I assume it’s directional in nature. I have seen in print several times that Camano 31 boats are capable of 20 knots.

 

[OldDan1943]

Do you have a trawler? Then think 5-8 knot speed aka hull speed. Putting a larger engine in the boat will not over come the hull design.
Semi-displacement hull (SD)? Planning, perhaps but at what cost? Fuel costs. The only advantage, in my feeble old mind, is you have the option to go above hull speed, when necessary ie, racing the tide or trying to outrun the weather or get to a dock or anchorage before dark. Remember, fuel usage is not linear. Once above hull speed, fuel usage/costs increase significantly.
Those of us who have a semi-displacement hull, run pretty much at hull speed of below. Why? To extend the distance between fill-ups. Example, at 7knts, 1200RPM, maybe 2000 miles. 17knts, maybe 380 miles. These are only projected miles. I dont know of anyone with a SD hull who runs WOT. Just not practical/economical. We adjust our speed for the sea state. With the SD hull, we have that option.
I used to run WOT (8+knts, when possible) in my Nordhavn but, I carried about 1000 gallons of fuel and really didn't care about fuel usage.
With this boat, there is a magic number for speed and GPH. LOL I only carry 400 gallons of fuel. Am I going for distance or speed. If I am going for distance and have the joy of passing someone tied to the fuel dock, sort of like the turtle vs the rabbit. The SD design is sort of like a sleeping lion..... go slow unless provoked.

 

[psneeld]

If you have ever run a semi displacement, lobster style with a very boxy skeg down keel....and high power.....you know when that boat is starting to get too much lift from the flat on the keel.


Bolger designs often hax a box keel that was questioned about ultimate speed performance.....

http://forum.woodenboat.com/showthread.php?157393-Bolger-box-keel-hull-speed-range&

 

[Nomad Willy]

Re the comments on the Bolger designs there were some very applicable remarks.

A man named “Sprit” was the only one w a bulls eye .. IMO
Spirt wrote; “ I suspect that the Champlain 22 has such a tucked up stern that it won't plane very well”. He realizes (correctly) that it’s all in the stern. There’s where you separate the fast from the slow. But it’s not always the stern. A boat w considerable rocker amidships will produce a boat that will respond to speed by it’s bow so high no tall man can see over it. And the stern will reside in the deep hole aft. Rocker is usually the operative hull shape on flat bottomed boats or with shallow V cross section made of steel or wood.

Many trawlers get the label SD from extra weight and a big keel. Neither have much or anything to do w hull form.
Dan, I don’t know anybody that runs a SD or any other inboard boat at WOT. If one feels the need for speed to that degree they would be much happier and better off w hull designed for those speeds. Dan writes ; “The only advantage, in my feeble old mind, is you have the option to go above hull speed, when necessary ie, racing the tide or trying to outrun the weather or get to a dock or anchorage before dark.” This is the part where many TF guys don’t understand. When Dan says “when necessary ie, racing the tide” Dan stubs his toe. You need to be introduced to the word “planning”. I’m not a planner and at times (not often) I need to go another route or hang on the hook. But usually my plan (that dos’nt exist) results in running 2-3 knots for up to several hours as I recall doing in lower Knight Inlet in BC. I may be dumb lucky as I’ve not had much of a problem bucking tides. But my point is that it’s not NECESSARY to do what you in fact WANT to do. I run at 6.5 knots (2500rpm) when the need arises but that’s it. FD cruising requires patience (some) and planing (some). Or extensive planning gets you down to the minimum inconvenience. But if you want to go anywhere anytime you’ve got to pay the price. And re my boat and bad weather is that in my experience that a good FD boat and some skills will get us through some really nasty stuff but w some anxiety and discomfort forward progress still happens.

 

[rslifkin]

Keels (especially a keel that's flat on the bottom and adds lift) definitely limit speed on a planing hull. I see it with my own boat. It cruises and handles very nicely at 17 - 18 kts. But there's a reason it's not powered to cruise faster without beating on the engines.

Push it up to 20+ kts and it feels fine in flat water, but you start to feel every little ripple as if you're on an 18 foot bow rider. And you can no longer make a tight turn with full rudder without things getting sketchy. Plus, if there's even a little bit of wave action (less than a foot), things feel a bit questionable at higher speeds.

Basically, between the lift from the keel and the general hull shape, the boat builds too much lift at those speeds and starts to plane too high out of the water where there's not enough hull in the water, but you still have that big keel down there to keep it from slipping sideways like a hull designed for higher speeds might start to do. So the handling gets a bit weird and squirrely.

The trade-off is that the keel adds directional stability at lower speeds (especially for a low deadrise hull) and the hull building lots of lift means it'll plane at lower speeds. With mine, I can slow down to 14 - 15 kts and it's still nicely on plane and not starting to fall off.

The Camano hull is very flat along most of its length, so I'd expect it to have a similar issue with lifting too high at higher speeds and having sketchy handling, as the amount of hull in the water can change suddenly (not a lot of deadrise, so easy to go from the whole hull in the water to just 1 side and the keel in a turn). My hull has about 10* of deadrise aft, the Camano appears to have none at all, so I'd expect the bad effects to come on a little sooner and much more strongly with the Camano hull.

 

[Nomad Willy]

rslifkin,
Very very interesting and otherwise good post.

I’m a little south of seeing how a keel can create lift. Huge amounts of drag yes..

My batts are down to 5%. Been looking at too much porn. I’ll be back after we get back from town.

 

[psneeld]

rslifkin,
Very very interesting and otherwise good post.

I’m a little south of seeing how a keel can create lift. Huge amounts of drag yes..

My batts are down to 5%. Been looking at too much porn. I’ll be back after we get back from town.

Not knowing how a potential lifting surface affects vessel dynamics.....well what I have been saying for years. B j

 

[rslifkin]

rslifkin,
Very very interesting and otherwise good post.

I’m a little south of seeing how a keel can create lift. Huge amounts of drag yes..

My batts are down to 5%. Been looking at too much porn. I’ll be back after we get back from town.

Keels do add drag, but a flat surface on the bottom contributes lift, much like a flat area of hull. And on a hull with some deadrise, that flat surface on the keel adds more lift than an equivalent amount of angle hull surface would. Plus the keel isn't necessarily level to the hull bottom, so it may have a higher angle of attack on its flat surface, potentially further increasing lift production.

Then there's the sides of the keel. Once you start to turn, the boat banks into the turn. Now the keel isn't vertical, so the downward side can end up producing some lift that isn't vertical relative to the hull. So this banks the hull into the turn further and helps lift the outboard chine higher. Once the hull is lifted high enough and banked far enough, the outboard chine starts to come out of the water and handling can get sketchy.

There's more than one reason that Hatteras made their keels smaller as they made the boats faster. Drag was part of it, but handling at higher speeds was also a factor.

 

[psneeld]

I for the life of me can't figure out how a person that has built boats and studied boat design as much as has been posted here still sees design issues completely differently than most other well versed boaters I know..... AND my personal experience.

 

[Nomad Willy]

rslifkin,
Keel lift .. hmmmmmm
Very small area to create lift and the bottom of the keel being only 2-3” wide .. even smaller lift. Then the water going toward the keel edges where it makes a 90 degree turn causing massive turbulence.
Hatt made the keels smaller just like (and for the same reason) rudders as speed increases.
If the flat bottomed keels were a problem why didn’t they round the buggers out? Tons of turbulence gone and lift 95% gone. But how many boats do you see w rounded keel bottoms? What ever lift is there must be really small.
Maybe FWT and others will have some other ideas. I wonder if prop walk and/or engine torque acting on the hull would have an effect?

Maybe it’s time to see a good pic of the CH after bottom. Anyone got one?

Perhaps there’s something other than the small box keel on the CH boat that’s a bit off.

 

[FWT]

Eric, I don't think the issue is in the keel per se. But that's nearly correct.

 

[FWT]

 

[Nomad Willy]

FWT, Thank’s so much for the pics and vid.
No mention of squirley stuff but it’s all promotional.
I love the way she runs about 9 - 10 knots (est). Multiple boats so multiple trim and displacements. But w some load (probably) she runs quite to very level. Could’a been a trim tab in there somewhere. If I was doing this I’d state that the demo boat did not have tabs.

The “hull-form” keel is not an Atkin or Bolger keel at all. It’s closser to a (long gone out of buss) boat that I had some 15 or so years ago .. a Sumner Craft. The SC had a much bigger and deeper keel than the CH. The SC as a 29’ 8,000lb boat was FG and cedar core strip planked. Had a Sabre 120hp and was capable of 20 knots. Interestingly the Ford based engine was about 80% down in the keel. There was a very slight “hook” to the bottom aft and she was extremely level riding.

The CH is much more like the SC than the box keel boats typical of Atkin and Bolger designs. Also the SC was a round chine design.

The pics of the SC are’nt as descriptive as I’d like so click on to make big.

Re the CH boats I see nothing not to like .. well the FB is (for my taste) too big .. or I’d rather it wasn’t there. Opps my batts are low again .....

 

[Frosty]

Re the CH boats I see nothing not to like .. well the FB is (for my taste) too big .. or I’d rather it wasn’t there.

Then the Camano Gnome would be for you:

 

[rslifkin]

I'd expect that at lower speeds, the bit of extra lift from the keel may be desireable. And if you really want to go fast enough to make it a problem, you're going to run into the side lift issue in turns anyway, plus you'd want to start reducing drag. So at that point, you just cut the keel down and maybe add more deadrise.


Plus, a flat spot on the bottom of the keel is likely advantageous when blocking the boat on land.

 

[FF]

https://www.boatdesign.net/threads/atkins-compared-to-modern-design-materials.52652/

Above is a discussion of Atkins box keel with reverse dead rise hulls.

Before WWII Atkins published many designs for home building.

Many ran near SL 2.8 instead of SL 1.34 with almost no wake, but then got wonky if pushed faster.

Speed of course is always a concern but these days a boat that can easily take the ground between tides (as some euro bilge keel boats do) would make lots of sense in crowded harbors, or for a no cost quick scrub and prop clean.

Not sure about battery powered boats , but a battery powered wire brush on the prop and running gear sounds grand.

A bunch of +++ for the older boaters.

 

[rslifkin]

Speed of course is always a concern but these days a boat that can easily take the ground between tides (as some euro bilge keel boats do) would make lots of sense in crowded harbors, or for a no cost quick scrub and prop clean.

That gives me an idea... For anything with a deep enough keel to protect the props (think Grand Banks), if you've got stabilizers, why doesn't someone make them strong enough to hold the boat up and ideally extendable? Want to clean the bottom? Let the tide go out and leave you aground, extend the stabilizers down as legs to keep the boat from falling over, then get to cleaning.



Other than the complexity of the legs and the need to have a deep enough keel, that would let you do this with whatever hull form you otherwise want (rather than making sacrifices in other ways to gain the ability to ground it safely).

 

[Nomad Willy]

rslifkin,
You’ve got one hell’ava sense of humor and ditto .. imagination .. saying “if you've got stabilizers, why doesn't someone make them strong enough to hold the boat up and ideally extendable?” Wow ..

Back to keels.
FF, Do these CH boats actually have reverse deadrise?
That would probably explain everything.
The only production boat I know of is the Shannon.
Again .. that would explain everything.
But do they? This thread has produced considerable discussion and I would’a picked up on that right away if it had been mentioned. Boats wide for their length universally have very high attitude trying to get on plane at “hump speed”. Look at the bottom image in post #13. The excessive beam for a boat 31 feet long is very evident shown w/o the swimstep. I was very impressed w the Shannon but the Shannon didn’t have a high bean/length ratio. But much more reverse deadrise.

So before I say another word about it .... does the Camano/Helmsman have reverse deadrise?

 

[Nomad Willy]

Anybody interested in this w any serious notions should read the Boat Design .net link FF provided. Especially the last two posts by PAR and Tom.

 

[Nomad Willy]

Frosty,
Thanks so much for the pics.
Had no idea it existed.
If they didn’t leave the extra heavy FB roof that most FB boats have and installed a lighter roof very noticeable performance improvements should happen.

But if I would be allowed to say so I submit that the FB version of the CH does, perhaps look better. ?? Did I actually say that?

 

[OldDan1943]

Supposedly there are/where cement cradles in the tidal area of Washington and Oregon that one can use as the tide goes out, everyone scrub the hull and running gear. I suspect the exact position of these cradles have been lost over the years because everyone now goes to the yard and pays folks to do what they could do for free.

 

[Nomad Willy]

Dan,
Fairly common in Alaska.
Here's Willy on the grid in Thorne Bay near Ketchikan.

 

[OldDan1943]

Dan,
Fairly common in Alaska.
Here's Willy on the grid in Thorne Bay near Ketchikan.

That is a good example. Just dont fall when going up to the dock.
How long before the tide comes in?

 

[Frosty]

Frosty,
Thanks so much for the pics.
Had no idea it existed.
If they didn’t leave the extra heavy FB roof that most FB boats have and installed a lighter roof very noticeable performance improvements should happen.

But if I would be allowed to say so I submit that the FB version of the CH does, perhaps look better. ?? Did I actually say that?

I agree. I love a no-fly sedan, but I think the Troll (flybridge) looks better than the Gnome in the Camano.

The roof is the same as far as I can tell. It even has the three molded flat spots for the fly chairs on it. A few were converted later from Gnomes to Trolls.

I'm going to guess the flybridge molding is not a huge weight disadvantage (unless one loads it up with stuff). It's a pretty simple "U-shaped" molding that sits on molded in spots around the perimeter of the cabin top. There are no cabinets under the helm - just open space. Three light chairs. There are the added stainless rails aft.

So it looks good, can shelter a few crab traps or etc., and isn't going to add much weight if one doesn't load it up (IMO). Obvsly a full oxygen tent will add windage, and one can pile heavy gear up on there if one wishes.

The one thing that makes me drool over the Gnome is how easy it would be to put un-shaded solar panels up there. But I think the Troll looks better proportioned.

 

[Greg S]

I had photos of the CH bottom, keel, hull etc. BUT, that was on a different phone. The one that went swimming.

NB: CH 31 is only 31 feet for bragging rights. Hull overall is 28. Advertising ploy to include the length of the ss anchor roller and the swim platform bolsters the owners ego, thinking they have a much larger vessel.

No. Not reverse deadrise. That was a question wasn't it? The characteristic that is bragged about the Keelform hull is that it doesn't squat and climb the bow wave. It stays almost level (not quite, but almost) right up until WOT. I could get WOT speed of 15 knots. Advertising claims as much as 18 but I suspect there is some trickery to go that fast with 200 hp.

Greg S

 

[Frosty]

NB: CH 31 is only 31 feet for bragging rights. Hull overall is 28. Advertising ploy to include the length of the ss anchor roller and the swim platform bolsters the owners ego, thinking they have a much larger vessel.

I don't believe that was the reason. Correct me if I'm wrong though. I thought they were going to try to sell them in Europe, and they require LOA as length. Similar to how the Nordic Tug 32 became 34.

If I remember correctly I saw this mentioned in an interview with Brad and Jaslyn Miller circa 2003 (the folks who bought Camano from Bob Warman in the late 90's and produced them until around 2007).

 

[Nomad Willy]

Greg,
Still have your Coaster? Daz a reel boat.
Thanks for “No. Not reverse deadrise. That was a question wasn't it?”

Well I think that must be the case. The CH performs much like the inverted dead boat tho.
I do see something not yet talked about. The cuped/hooked corners on the bottom aft. No doubt to help cope w squatting. But with such a wide beam if one corner was doing it’s thing and the other was’nt a bit of asymmetrical lift on only one corner could conceivably cause strange things to happen. In high banked turns it could/would be a plus .. controlling overbanking.

But the only significant thing I see is that the high volume keel providing lift or hull support on C/L could cause a bit of roll tenderness at higher speeds .. or even low speeds. But I see that as what deep deep V hulls cope w “every day”.

And if I was shopping for a CH this issue or tendency would be far from my mind .. as something that can’t even be identified and pinned down can’t be of any consequence.

But maybe the person w the holy grail is holding out?

 

[NCheaven]

Biased

Owning a 2005 Camano FB model (I don’t use the “Troll” name), I’m a biased fan. I find moderately tight turns over 3,000 RPM up to WOT to be quite smooth, minimal lean. I don’t peg the wheel, as I do this as a handling exercise, putting some hull cleaning pressure on the chines, and not an endurance test. The Camano handles predictably at all speeds and all conditions, with stern seas of 3’ and more being predictably sloppy.

The bow is not purely straight, and I calculate hull speed off of 27’ WL. I don’t know the real #.

I do run at WOT a few minutes now and then as a way of evaluating metered engine Temp, RPM, sound, metered GPH, etc, taking in the feed back, and backing down to 3200 RPM for exhaust system clean out for a 15 min or so. (14.4 kt@ 3750 RPM, 190 F, 10 GPH floscan at WOT w/ OEM 20x18 prop., 50% water and fuel, 2 souls.).

I have no plans to cruise @ 12 kt, 14 kt, etc. That’s for narrowing weather windows, etc. on my watch. Others choose different cruise plans, fine for them. 6.5 kt is fine for short segments. 6.8 is normal 2/3 day segments. I’ve stretched daylight with long runs in 7.2 to 7.8 kt segments. After 8.2 kt I feel I’m putting excess strain on running gear and that moving toward 12 kt as the wiser choice, but that’s a personal choice, not a recommendation.

In NC’s thin coastal/inland water the Camano is a great choice for us, seaworthy, reliable, and efficient. Coming from Bristol RI to NC on the delivery cruise was a dream come true, whether off shore in the Atlantic, running the length of the Chesapeake, or across notable Albemarle Sound. The classic form fits function design draws compliments in all ports, and the amazing visibility from the cabin helm station is a great safety asset. The flybridge is a pure delight, underway or while slow dancing on the hook or in port. Only if I have severely compromised mobility would I do without the FB, but that is another personable preference, not a matter subject to debate.