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Old 23-05-2013, 07:24   #31
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Re: Build a Boat for The Great Loop?

By the way, Fast Cat II was built by Gold Coast Yachts--see the picture at the bottom of the page at this link: Gold Coast Yachts Custom Boat Builder ? Power Catamarans.

And here is a one-page brochure: http://www.goldcoastyachts.com/Comme...P-features.pdf

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Old 23-05-2013, 08:43   #32
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Re: Build a Boat for The Great Loop?

If you just think it's a cool design and don't care about the cost, go for it but it seems like a whole lot of complicaton for minimal benefit.

How much are the folding extensions going to cost against the potential extra slip fee savings?
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Old 23-05-2013, 12:53   #33
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Re: Build a Boat for The Great Loop?

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Originally Posted by ewsponberg View Post
The hinge on top would be preferable, in my opinion, and opposite that there has to be a heavy-duty positive latch mechanism. The latch and the movement of the bow opening and closing can both be hydraulically operated. The thing that you have to appreciate is that when the boat is running in normal closed configuration, the hydrostatic and dynamic forces on the hulls forward of the joint are going to be huge. Normally, the hull skin and its internal stiffening would handle the stresses. Now with the joint, you are breaking the skin and structure, so all those loads have to go through the hinge and the latch. You've got high loads pushing up on the hull (and down, for that matter as the bows pierce the waves) and a long moment arm forward of the joint (halfway between the joint and the bows, approximately). These have to resolve themselves into much higher loads on a relatively short moment arm (the distance between the hinge and the latch); the moments have to be equal and opposite. Plus, the hull sides experience high shear stresses running vertically up and down the hull at about ±45° to the hull axis, but the joint breaks their path. So there are all sorts of stresses that have to concentrate into relatively smaller parts. The hinge and latch parts have to be big enough to handle all these loads. That's why I say the idea, while commendable, will be difficult to

I'm just thinking out loud here, trying to point out the engineering obstacles that have to be overcome. I'm not saying it can't be done, but some real good thought should be applied to making the parts large enough and reliable enough to work.

I have another thought, however, that may obviate the need for foldable bows. The point of the original design as offered was a wave piercing hullform. The example boat has really long bows. The bows don't have to be that long--they can be much shorter and still accomplish the same thing--relatively low drag and easy motion. Many wave piercing catamarans have been built with accommodations nearly the full length of the wave piercing bows, so maybe this is a problem that does not have to be.

Eric
There's another boat here in KW that is a shorter cat... I'll get pix!
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Old 23-05-2013, 13:37   #34
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Re: Build a Boat for The Great Loop?

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Originally Posted by valhalla360 View Post
If you just think it's a cool design and don't care about the cost, go for it but it seems like a whole lot of complicaton for minimal benefit.

How much are the folding extensions going to cost against the potential extra slip fee savings?
His entire design concept for a Great Loop boat is irrational. A power cat is good for stability and speed in a chop, neither of which he is interested in or required for a Great Loop boat. Fold it in half to save dockage expense----very foolish.
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Old 23-05-2013, 13:49   #35
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Re: Build a Boat for The Great Loop?

Some folks are educated far beyond their intellegence
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Old 23-05-2013, 14:01   #36
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Re: Build a Boat for The Great Loop?

When my boat was still going have sails, my thought was to make long folding bowsprits, which has been done before. As they would not be needed extended in port.
For actual hull, not sure it is worth it, just don't spend time in marinas, that is my plan so I can go to 50-60ft on a 30ft budget.
And sorry, but think that boat is ugly, at least make one slick looking.
The tall slab-sided power boat is about the worst possible for windage,
a "sailboat design" cat looks much better.
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Old 23-05-2013, 14:07   #37
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Re: Build a Boat for The Great Loop?

According to my wife the perfect boat for the loop would be a diesel version of our 50' Gibson. I can't say I disagree.
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Old 23-05-2013, 14:09   #38
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Re: Build a Boat for The Great Loop?

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Originally Posted by nimblemotors View Post
And sorry, but think that boat is ugly, at least make one slick looking.
"Fugly" might be more apropos. (Not that I'd ever accuse a forum moderator's dreamboat of glaring repulsiveness.)
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Old 23-05-2013, 14:31   #39
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Re: Build a Boat for The Great Loop?

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Originally Posted by capngeo View Post
I've been approached to build a boat for a friend specifically for the Great Loop. Over a few beers we decided on a powercat of modest dimensions. The overall design would be based on the Sunnydays boats here in KW


The departure from that design would be hinging the forward sections of the hulls to fold inward, saving LOA for locks and dockage. The hulls and deck would be either steel or aluminum and the house wood/fiberglass. Power would be small outboards just inboard of each hull on a liftable frame... up for skinny water, down for maximum performance. 10kt cruising speed target, 250 mile range, 5 day endurance.

Let the comments fly!
Why would you really want those wave piercing hull shapes for a great-loop boat that will spend the great majority of its time in rivers, canals, lakes? It would be a much easier build to not include them.

I've got a few other ideas for you, but first let me look thru this subject thread (just started)
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Old 23-05-2013, 14:43   #40
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Re: Build a Boat for The Great Loop?

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Blah....some of the best engineers aren't!!!!
Quote:
Originally Posted by kmacdonald View Post
Name one!!!!!!!!!!!!
Robert Goddard....the father of American Rocktery

He didn't start out to study engr
....he eventually studied science and physics

Robert H. Goddard - Wikipedia, the free encyclopedia
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Old 23-05-2013, 14:47   #41
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Re: Build a Boat for The Great Loop?

Quote:
Originally Posted by ohdrinkboy View Post
Samuel Seaward
1800-42
Cranes, dredgers, swing bridges and many other inventions
A pupil of Henry Maudslay
John Smeaton
1724-92
Civil engineer. Researched the mechanics of waterwheels and windmills. Lighthouse design e.g. Eddystone. Improved the Newcomen atmospheric steam engine
School/Apprenticeship. Worked as a mathematical-instrument maker.
George Stephenson
1781-1848
Railway engineer. Steam locomotives
Evening classes three nights a week paying 4 pence a week. Gained direct work experience in mining engineering /Apprenticeship
Robert Stephenson
1803-59
Mechanical and structural engineer. Steam locomotive design/bridges
Self-taught with help from his father George. Attended a village school and then his father sent him to a private school and then apprenticed at Killingworth Colliery which he did not complete but then gained valuable experience in railway engineering
Jedediah Strutt
1726-97
Knitting machines worked with Richard Arkwright
Self taught: started as a farmer
Thomas Telford
1757-1834
Civil engineer. Canal/road engineer e.g. Caledonian canal started in 1804. Innovative Aqueduct and bridge design and construction.
Attended a local parish school. Apprenticeship (Stonemason) Langholm and self taught.
Charles Tennant
1768-1838
Chemist and industrialist. Textiles/Dying
Studied at a local school then apprenticeship as a silk weaver
Richard Trevithick
1771-1833
Engineer and inventor. Steam engine (High-pressure steam engine 1800
Attended a local school but largely self taught and became a mining engineer
Jethro Tull
1674-1741
Agriculturalist. Seed drill (1701)/Introduction of improved farming methods
Oxford university
James Watt
1736-1819
Engineer and inventor. Steam engine design/Lunar Society
Taught by mother then some formal schooling-Greenock Grammar School and eventually gained experience as an instrument maker at Glasgow University. A mechanical genius who was very versatile.
Josiah Wedgewood
1730-95
Chemist specialising in pottery/Lunar Society
Self educated/Apprenticeship (Pottery/thrower) but because of ill health broke the indenture and experimented with decorations, clay types and furnace technology.
Joseph Whitworth
1803-87
Engineer and inventor. Machine tools/Screw threads. Planing machines, a power- driven self-acting machine and measuring machines. Established the Whitworth scholarships.
Attended his father’s school then as a boarder at a private school at Idle near Leeds but left at 14. Apprenticeship (Cotton spinning) and gained valuable work experience in Manchester and London engineering companies including the Maudslay workshops
John Wilkinson
1728-1808
Ironworker and inventor. Boring machine
Learnt working at his father’s side
WOW, good list.
I guess I should have read a little further before I made my posting
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Old 23-05-2013, 15:07   #42
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Weekender, Picnic Style Powercat

These were taken in Thailand.

I titled it weekender/picnic boat, but really she is large enough for a nice long cruise.

The vessel I posted actual has some accomodations in the hulls. Its just that the majority of the 'living' area (saloon,cooking,etc is up in this central 'between the hulls' covered deck space. (note there are 4 hatches down into the hulls)

And the outboards were a cheaper, less intrusive manner to add power.
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Overall a nice concept....that could even lend itself to home building in composite ply. Have a look here.
DH 550 Plywood Cruising catamaran
DH550 radius chine plywood catamaran building photos

I have some more photos of that Thai boat if you're interested
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Old 23-05-2013, 15:20   #43
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Large Cat with Outboards

You might have a look thru this other subject thread as well. I just found that I had posted this info over there as well.

Who Makes a Large Catamaran with Outboards
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Old 23-05-2013, 16:07   #44
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pirate Re: Build a Boat for The Great Loop?

I reckon Wharram Tiki 36 hulls with a topsides of your own design...
Shallow draft, proven sea kindly hull and able to be easily folded up on deck with a deck hinge and the help of a winch. held in place on either side of the V by a locking pin each side running from deck to the keel...
Mind... Ply with good glass and an alloy sacrificial keel shoe would be adequate I reckon..
Just had a thought... make it with a second bow... a v within a V... so if anything went wrong you'd still have a manouverable boat as opposed to two blunt bows... or is that getting to silly...lol
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Old 23-05-2013, 17:02   #45
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Open Saloon Types

...a few other good photos, and some other 'open saloon styles'
Weekender/Picnic PowerCat - Page 2 - YachtForums.Com
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