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Old 07-25-2013, 11:27 PM   #41
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Patented

I believe the Shannon SRD hull tecnology claims to be patented. I wonder how that equates with the Gerr hull shape??
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Old 07-25-2013, 11:35 PM   #42
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....from posting #265 on that other forum discussion
Help With Economical Semi-Planing Designs - Page 18 - Boat Design Forums


Quote:
Originally Posted by kengrome
ALowell, I don't see how you can question the utility of the tunnel-stern Seabright design when it offers more features than your current boat -- the first of which is shallow draft -- a feature that perhaps others find more useful or appealing than you do.

Another very practical feature is the boat's ability to be beached almost anywhere there is a beach.

Another feature is its ability to sit upright on its flat bottom box keel when on the beach or on a tidal flat, or even on a cheap flatbed trailer.

Another is its excellent fuel efficiency which is very hard to match in almost all other planing power boats because of the way the tunnel-stern Seabright design re-uses the energy trapped in the accelerated boundary layer water. There are other threads that explore this unique phenomenon if you are interested.

Your lobster boat may be a great boat, and it may actually be a better boat for you than a tunnel-stern Seabright skiffs. But shallow draft is very important to many people, and so is fuel efficiency. For these two reasons alone I think many people will prefer the tunnel-stern Seabrights.

Unlike you, I never worry about how difficult the boat might be to build either. Instead I prefer to focus on the features I want from a boat, then do whatever it takes to build that boat, even if it requires more effort or takes more time during construction. Then I will end up with the boat I really want, rather than something that only comes close.
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Old 07-26-2013, 01:16 AM   #43
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I know absolutely nil about hull or boat design Brian but as unique as it may be below the waterline I really like what is above the waterline.
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Old 07-26-2013, 01:54 AM   #44
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Either someone is really clever...or not....remember Ben Lexcen....
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Old 07-26-2013, 07:21 AM   #45
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The problem with radical new bottom designs is that often they are not new...people have been toying with ideas for decades if not centuries and it's hard to believe that all of a sudden...there's a new, practical and workable idea.

You don't think the Navies and Coats Guards of the world haven't been pushing for stuff like this for years?

Just because there's a computer drawing of a new design out there doesn't mean it's all that "workable".

Penn Yan had an old tunnel drive that went into shallow water very well from what I could tell but I also heard it handled very poorly, wasn't economical compared to others in it's class, etc..etc and that boat made it well into the production phase.
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Old 07-26-2013, 07:30 AM   #46
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All that work, they could have at least cut a transom door in the cockpit. Is that so difficult?
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Old 07-26-2013, 07:37 AM   #47
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I'll second that. Shoal draft tugs have been built and working the rivers of B.C. and Alaska forever. A 90+ foot boat with 44" draft is normal. Years ago I worked on a 65 foot twin screw tunnel drive tug built to churn and bore its way up through gravel bars to a mining camp. We used 4 blade stainless steel props that looked like meat cleavers at the start of a trip and normal props by the time it was over.

The internal volume lost to the drives on a hull like that illustrated must be a high price to pay unless the owner has to choose between that and not being able to go someplace important.
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Old 07-26-2013, 08:15 AM   #48
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Quote:
Originally Posted by CPseudonym View Post
I know absolutely nil about hull or boat design Brian but as unique as it may be below the waterline I really like what is above the waterline.
I liked them also, but placing that big stateroom at the rear instead of the great salon and aft deck of the Pilgrim design just didn't cut it with me.

Gerr's boat
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Old 07-26-2013, 08:27 AM   #49
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Originally Posted by psneeld View Post
The problem with radical new bottom designs is that often they are not new...people have been toying with ideas for decades if not centuries and it's hard to believe that all of a sudden...there's a new, practical and workable idea.

You don't think the Navies and Coats Guards of the world haven't been pushing for stuff like this for years?
I know of a number of 'advanced thinking' designs that have NOT been adopted by the USA Navy, nor the USA Coast Guard. ...old conservatives (polite for old fogeys)


Quote:
Penn Yan had an old tunnel drive that went into shallow water very well from what I could tell but I also heard it handled very poorly, wasn't economical compared to others in it's class, etc..etc and that boat made it well into the production phase.
Admittedly I think both camps would say some of their development was based on the Penn Yan work. But the Penn Yan designs were principle about putting a recessed tunnel into the conventional v-bottomed hull to gain a shallow draft. Correct me if I'm wrong, but they did not get into reverse-deadrise territory. (Pardon me, I'm not a powerboat guy, so I'm now learning about powerboat hulls)
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Old 07-26-2013, 09:20 AM   #50
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Quote:
Originally Posted by brian eiland;[SIZE=3
170135[/SIZE]]I know of a number of 'advanced thinking' designs that have NOT been adopted by the USA Navy, nor the USA Coast Guard. ...old conservatives (polite for old fogeys)Not adopted because they didn't work anywhere's near advertised in most cases or what was given up was too much.

Admittedly I think both camps would say some of their development was based on the Penn Yan work. But the Penn Yan designs were principle about putting a recessed tunnel into the conventional v-bottomed hull to gain a shallow draft. Correct me if I'm wrong, but they did not get into reverse-deadrise territory. (Pardon me, I'm not a powerboat guy, so I'm now learning about powerboat hulls)
My point is not so much about "that" particular failure as much as MANY new designs are just tweaks of older designs that still may or may not work.

Just because some "naval architect" ran the numbers and drew a design isn't a success story...yet. Until tank tested and then tested in full scale versions under a variety of conditionons
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Old 07-26-2013, 10:35 AM   #51
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WHAT?

psneeld you expect somebody to design a new boat that dosn't look like a boat?
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Old 07-26-2013, 11:31 AM   #52
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What????
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Old 07-26-2013, 12:04 PM   #53
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The ad says,"This 32 Island Gypse has many upgrades and is in a class by its self, you will never find another like her. This boat has new fuel tank as of 2013, she also has many upgrades that are not found on a 32 Island Gypse.

Click on the link and view the "photo Gallery".

Island Gypsy

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Reminds me of Vinal Window retrofit - Not too bad an idea if you want to alter bottom design for any boat. Simply build the bottom form, plug boat inside, calk/fasten well - SPLASH! LOL

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Old 07-26-2013, 12:08 PM   #54
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There have been a number of these Gerr boats built and out there operating. I don't have the time at this moment to quote the hold Passagemaker article, nor a number of others written about these designs, but here is a short excerpt.
Quote:
Originally Posted by PassagemakerMag
Belle Marie cruises at a solid 10-11 knots, topping out at 11.5. At 11 knots, she consumes about 3gph,....This steady, continuous, confortable cruising speed,...11 knots on a 39'5" waterline is quite unusual. It corresponds to a speed-length ratio of 1.75. This is true semi-planing performance. Yet at 11 knots, Belle Marie makes no fuss at all going thru the water. She maintains level trim, throws no large wake, and in every respect behaves exactly as if she were operating at the standard displacement speed for this waterline of just 8.5 knots
She's equipped with a single 220 hp Cummins
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Old 07-26-2013, 12:32 PM   #55
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Quote:
Originally Posted by brian eiland View Post
There have been a number of these Gerr boats built and out there operating.
IIRC, Gerr recognizes the Hickman Sea Sled for his design inspiration.

Hickman doesn't get near enough credit for his design work...
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Old 07-26-2013, 01:06 PM   #56
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Looks like a pontoon boat to me...
That was what I was thinking or put on top of a couple of Kayaks!!!
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Old 07-26-2013, 04:00 PM   #57
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Crowther Coast Guard Catamran

Quote:
Originally Posted by brian eiland View Post
I know of a number of 'advanced thinking' designs that have NOT been adopted by the USA Navy, nor the USA Coast Guard. ...old conservatives (polite for old fogeys)
Just one example. Quite a few years ago, the US Coast Guard was looking for a replacement vessel for their 82' patrol boats. Several things they wanted:
1) Good turn of speed
2) Economical to operate
3) Helo pad
4) Fast launching RIB capability

This design by Lock Crowther would have fit the bill VERY nicely. I tried to get the option to submit the proposal. I was even allowed to submit.

BUT it was before catamaran forms became 'acceptable', and it was designed by a foreigner (Australian).

Shortsightedness
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Old 07-26-2013, 04:36 PM   #58
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Quote:
Originally Posted by brian eiland View Post
There have been a number of these Gerr boats built and out there operating. I don't have the time at this moment to quote the hold Passagemaker article, nor a number of others written about these designs, but here is a short excerpt.

Originally Posted by PassagemakerMag
Belle Marie cruises at a solid 10-11 knots, topping out at 11.5. At 11 knots, she consumes about 3gph,....This steady, continuous, confortable cruising speed,...11 knots on a 39'5" waterline is quite unusual. It corresponds to a speed-length ratio of 1.75. This is true semi-planing performance. Yet at 11 knots, Belle Marie makes no fuss at all going thru the water. She maintains level trim, throws no large wake, and in every respect behaves exactly as if she were operating at the standard displacement speed for this waterline of just 8.5 knots


She's equipped with a single 220 hp Cummins
Those numbers don't make any sense......3gph is just above a high-idle for the 220 Cummins, it's about 65 HP......Does the boat really require another 150HP to get another 1/2 knot? At 2500 RPM that engine will go through over 11gph, and with all that HP she should do well over 12 knots......
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Old 07-26-2013, 05:09 PM   #59
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Those numbers don't make any sense....
Perhaps you should write Passagemaker mag and/or Dave Gerr and ask them to explain these numbers?

I don't know Tad, I just quoted the article.
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Old 07-26-2013, 07:51 PM   #60
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I think they will be lucky to get $30K for it as it sits.
Maybe on the water it could be a winner. If I were boat shopping in that area, I would want to test drive it and that could sway my opinion. I think it would be a great river or lake boat.
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