Atkins - compared to modern design/materials

(I wasn't sure if this was a "design" thread or "powerboat" thread)

Has anybody looked at the Atkins designs (power boats) and run them through modern software simulators? Of course the old engines can't compare to modern ones but I wonder how well the "old" hull designs would compare (safety/stability etc) to modern boat of the same intended use/size.

Do people even build these boats anymore? I'm talking about boats 24' or more.

 

"The Atkins designs" of powerboats run a very large range of hull forms and configurations, across the boards of both Billy and John. John's last powerboat commission was a 37' "bill boat" which I own, built in 1960. As to your question, I don't suspect any real attempt to computer model, the bulk of these hundreds of designs, nor make performance predictions has been done.

If you're familiar with yacht design, you'd know these various hull forms are fairly typical for their era's, so if you have a John Atkins runabout from the 1950's, you'll know it's a modest deadrise, warped bottom, probably with a fairly deep forefoot, compared to newer models or more modern designs. Typical for the era.

Yes, lots of folks are building these designs and a few builders are specializing in some of them, such as the tunnels hulls or the box keels, etc. If thinking about an Atkins design, remember, we've learned quite a bit in the 1/2 a century since the last one was drawn up, plus building techniques and materials have changed considerably as well, so you'd be well advised to access your requirements, develop a solid SOR on them and search based on these needs and desires.

 

Not a bad business model is it, still bringing in revenue after all those years. Can't say that about too many things that old.

 

The shear volume of the Billy and son team, insured a long run, even after their deaths. Pat (John's wife) has also had a lot to do with continuing the interest, so . . .

Standpipe, maybe it would be easier if you narrowed down the hull form interest.

 

Thanks for the information Par. I was wondering if the designs fell under the catagory "timeless" or "dated" and you've answered the question.I've seen the Rescue Minor design being built and other tunnel designs ...but the rest....

Pretty good work if you can get it

 

I think if you want an antique design, then go for it, but if you want an antique looking design, with modern build methods and employing modern materials, well, now this is a different beast, which will likely be faster, lighter, stiffer and possibly more efficient too. In the end, you have to nail down what you're looking for, then focus of these types of designs.

 

I've browsed the Atkins designs fairly often and find some very interesting. There isa perfect beauty in these boats that seem timeless in some designs but most are so dated they wouldn't be practical in todays world.

But some of the V and flat bottomed inboard boats may make great outboards but there are issues to address like fullness in the wrong part of the hull and CG problems highly related to the former.

There are wonderful examples that have been recently built like Russell R. I'm personally interested in the V bottomed Ketewomoke and Tang. Marcia, a flat bottomed inbd cruiser would gracefully transform into a trailerable OB if built in plywood.

 

To me the most interesting of the Atkins boats are the Box keel , reverse deadrise boats.

We know SWATH works and lifting the hull by using the keel volume looks like a good idea.

The bottom of the keel might provide lift as a water ski would

With the prop parallel to the water another few percent in efficiency is gained.

The reverse dead rise seems a good way to stop squatting at modest speeds (these are below full plaining hulls) SL up to 2.8 or so.

They look like a number of ideas that are current , 50 years later for some one that wants to cruise faster cheaply but not go plaining speeds.

I also love the beachable concept.

In the NE many mooring or anchor places have been grabbed by the local townships to drop moorings to extract cash from cruisers.

The ability to anchor well In shore and take a bit of tide looks like a grand idea.

Weather extra efficiency comes from using the already accelerated water along side the box keel to feed the prop remains to be seen , but its possible.

 

http://www.atkinboatplans.com/Cruisers/FriarTuck.html

This 40' twin screw patrol boat would fly in the modern world as a fast trawler. The semi planing pointy stern has merit IMO. Looks fairly efficient too.

 

None of these have been demonstrated as true, only speculated on. The reverse deadrise and down angle of the aft tunnel does provide lift but, and its a big but, the water must first be lifted up into the tunnel. At best its a wash and the Rescue minor I drove seemed to be firmly attached to the water, indicating to me that there was a net negative lift going on.

The tunnel of Rescue Minor has been attributed to have magic associated to it but, in my view, its just a great shallow water boat.

 

"The tunnel of Rescue Minor has been attributed to have magic associated to it but, in my view, its just a great shallow water boat."
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Rob Whites claim was 35 nmpg or so, a fantastic number today!

 

35 nmpg, how would that happen ? That was probably going over Niagara Falls !

 

Robb was known to stretch or shrink things, depending on which was more suitable to the point he wanted to make at the time. Even so, I never heard anything as unlikely as that.

Several Rescue Minors were built or started during the extended discussions taking place on the forum at the time. I've never heard of results from any of them that backed up any of the great claims and most were never heard of again. That is very telling that the magic failed to appear. I've known of two locally and driven one. Good shallow backwater boats but I would never venture into rough stuff with one.

Someone makes some outlandish claims and others use up lots of brainpower in the attempt to explain how it works but no one actually makes demonstrations that prove or disprove it. Whatever the claim, it ain't any good until its demonstrated. Its called peer review, otherwise its just talk.

 

The reversed deadrise hulls that Atkins drew up where started by Billy, then developed by John. The initial idea was to decrease the size of the hook, with additional dynamic loading under the stern, given the power to weight issues Billy had to contend with. By the time John started to play with them, the power to weight issues decreased dramatically and this became less a problem, but some more thought was applied to continue the idea. Most designers of these eras employed a hook of some sort to control trim.

At low speed and with a relatively low top speed target, these narrow, reversed deadrise forms can offer some modest efficiency boosts (engine size and fuel use) over more conventionally shaped boats of similar length. Their biggest advantage is the ability to ride the bow wave, instead of climb it, at certain semi-displacement speeds and the seemingly humpless transition to low full plane mode. Though I'd like to test a skinny clam skiff against a Rescue Minor with the same engine, length and beam, just to see how much (if any) improvement can be realized. If anyone has one of these and is in central Florida, I run a 17' skiff against them, with a 10 or 20 HP outboard to see where they compare.

As Tom has noticed, if you study wave trains on these hull forms, they really don't "jump up" on plane, though they can exceed a S/L of 3.2 or so, the wave train suggests there's something "left" before the hull is in full plane. It's fairly difficult to describe, though if you look at the wave train, it becomes pretty obvious. In a nut shell the hook's shape is key and limits high end potential and the reversed deadrise helps get the boat out of displacement mode much quicker than conventional shapes. It's a lot easier to do this with strake shapes, at least in terms of building. Coupled with a narrow WL beam, S/L or 3.5 can be possible, but I'll bet this has more to do with the narrow WL beam and light weight, than the dynamics under the hull. I'll bet these hulls where simply development of their (seemingly) fascination with the Sea Bright shapes.

With a good close look at the way these boats run, you see they penetrate the bow wave, but instead of climbing, they ride over it a bit, until the midship deadrise comes to bear and then sort of surf on their forward quarters, much like early planing dinghies. If power is increased, they start to squat, but not as much as V and flat bottoms, but drag also starts to increase dramatically as well (the hook bites harder), so they max out, stretching the stern wave, but it remains attached. There's a good video of Robb's Rescue underway in shallow water that clearly shows this attribute at the end of the clip as he's motoring off at WOT. The hull take s a2 degree set, instead of the 3 to 5 of a conventional hull and she just plows along, until drag overcomes the power output. If you've studied wakes like I have for a long time, it's not a pretty wake as powerboat wakes go, though at some speeds can be advantageous. So, if looking for a skinny waters powerboat, that lacks elbow room, must be built lightly and has a top speed in the low to mid 20 MPH range on a fairly small engine, this is one route to employ.

 

Paul,

Robb built his version of the Rescue Minor very light and we don't know what is under the bottom of that boat. At no time and under no circumstance could the boat I was in reach the mid 20's or even 20mph. In fact a bit over 13 kts was its limit and the power was per specs. As some others, including Robb, have noticed, the boat seems stuck to the water.

The shape of the Sea Brights is known to have advantages and serves well in the environment it was developed for. I have strong reservations that either RM or SB could equal the performance of your skiff in open water testing. If that were to happen, it would show that designers and builders have been on the wrong path for a very long time.

I'm not knocking either RM or Atkin but anyone expecting miracles will likely be disappointed.

"Coupled with a narrow WL beam, S/L or 3.5 can be possible, but I'll bet this has more to do with the narrow WL beam and light weight, than the dynamics under the hull. I'll bet these hulls where simply development of their (seemingly) fascination with the Sea Bright shapes." ........I think you've got it.