Cargo Sharpie Design

[gonzo]

The main advantage of the sharpies is their simple design and shallow draft. Each time a contraption gets added to them, they become worse. It is a type that evolved through a long time of work experience and trial/error and became very refined.

 

[Schooner Guy]

Putting in a full ballasted centerboard on a large cargo sharpie entails something like 15,000 pounds on the board bottom. A daunting design.

I got to thinking about Bolger's 30' sharpie and correct ballast. So here is an alternative attack.

Use no ballast. Put in a dive plane like fin affair about amidships. Each plane side goes opposite of the other giving a water speed caused torsion to counter act sailing heel.

The more heel the higher the available torsion because heel means speed and power.

No ballast for self righting means a normal trawler like upper structure to cause return to upright.

The drag of the planes can use excess sail power once the hull speed is attained. In light winds the plane angle can necessarily be zero meaning little drag.

They are not stability planes for wave action unless you build in a dual use.

Thank you for your opinion DouglasEagleson

 

[Rurudyne]

It seems to me that vast majority of centerboards have not been fully ballasted, or indeed anything but somewhat heavy, and they've apparently done just fine.

SchoonerGuy, have you considered giving up some of the displacement for the given draft associated with a true flat bottom boat for a deadrise type like a skipjack or something like a scaled up Seabird, which would be even lighter? For a coastal trader weight is not an issue, indeed a virtue as it represents capacity, also the more luxurious the modern yacht the worse the bloating, but there is a lot of experience from many quarters with comfortable cruising that can do with less than posh, and it has been extensively written about.

If you go to Google Books you can find annuals for The Rudder magazine for most of the first two decades, and some of the third, of the 20th century and with them numerable articles that would still be relevant to the sort of boat you now wish to build (which is not a latest-greatest hull form by any measure, though respectable). These can be downloaded in PDF form for free.

 

[Schooner Guy]

It seems to me that vast majority of centerboards have not been fully ballasted, or indeed anything but somewhat heavy, and they've apparently done just fine.

SchoonerGuy, have you considered giving up some of the displacement for the given draft associated with a true flat bottom boat for a deadrise type like a skipjack or something like a scaled up Seabird, which would be even lighter? For a coastal trader weight is not an issue, indeed a virtue as it represents capacity, also the more luxurious the modern yacht the worse the bloating, but there is a lot of experience from many quarters with comfortable cruising that can do with less than posh, and it has been extensively written about.

If you go to Google Books you can find annuals for The Rudder magazine for most of the first two decades, and some of the third, of the 20th century and with them numerable articles that would still be relevant to the sort of boat you now wish to build (which is not a latest-greatest hull form by any measure, though respectable). These can be downloaded in PDF form for free.

I really like this design and since I am planning on building in steel this is a easier type of hull to build it also has ocean capability's and would be an amazing boat draft wise for the islands they also are very capable when it comes to cargo and are quick under sail. I know they are not the latest-greatest hull but I'm not crazy about the latest-greatest hulls

 

[philSweet]

Just a couple random comments. Flat bottomed sharpies were really good at high cargo ratios. Built like a Newhaven type, they could carry 8-9 times their dry launch weight in oysters and mud. Heeled to the rail, they produced almost constant righting moment (at ever decreasing heel angles) as they got heavier. But not many people need a yacht that can carry 8 times the lightship condition. And that suggests that better shapes than a dead flat bottoms can be used to advantage. For a liveaboard yacht with some cargo capabilities, The difference between light ship and fully burdened might only be a factor of 2 or so. If the bare ship comes in at 40,000 pounds, and you carry 2,000 pounds of lead as trim ballast, and 10,000 pounds of water ballast, and 3000 pounds of personal stuff, you end up around 55,000 pounds for a no cargo condition. That would let you carry about 30,000 pounds of cargo by dumping tanks and letting draft increase by 1'. Designing a boat for that range in load isn't nearly as tricky as for greater load ratios as long as it is fairly dense and can be packed efficiently. And even at 3'6" draft no cargo, 4'6" in full load, you can do better than a flat bottom. File bottom sharpies evolved for yacht duty and some very nice ones were built over the years.

 

[CT249]

Putting in a full ballasted centerboard on a large cargo sharpie entails something like 15,000 pounds on the board bottom. A daunting design.

I got to thinking about Bolger's 30' sharpie and correct ballast. So here is an alternative attack.

Use no ballast. Put in a dive plane like fin affair about amidships. Each plane side goes opposite of the other giving a water speed caused torsion to counter act sailing heel.

The more heel the higher the available torsion because heel means speed and power.

No ballast for self righting means a normal trawler like upper structure to cause return to upright.

The drag of the planes can use excess sail power once the hull speed is attained. In light winds the plane angle can necessarily be zero meaning little drag.

They are not stability planes for wave action unless you build in a dual use.

The basic idea has been tried - and abandoned. To give just one of the basic flaws of the concept, it provides little if any self-righting force when you will most often need it - that is, after a broach when the boat is moving slowly. Similarly, you have little if any self righting after blowing a tack, or being caught aback - the sort of times when you really need self righting moment.

How will a trawler-style superstructure assist in righting a boat to the stage where it can once again develop sufficient speed through sails to get the foil working properly once again?

Have you tried sailing something like an International Canoe, or a wide-wing 18 Foot Skiff? They give you a good idea of the difference between being at an equilbrium at speed, and having a chance to recover when it all goes wrong.

 

[Schooner Guy]

Just a couple random comments. Flat bottomed sharpies were really good at high cargo ratios. Built like a Newhaven type, they could carry 8-9 times their dry launch weight in oysters and mud. Heeled to the rail, they produced almost constant righting moment (at ever decreasing heel angles) as they got heavier. But not many people need a yacht that can carry 8 times the lightship condition. And that suggests that better shapes than a dead flat bottoms can be used to advantage. For a liveaboard yacht with some cargo capabilities, The difference between light ship and fully burdened might only be a factor of 2 or so. If the bare ship comes in at 40,000 pounds, and you carry 2,000 pounds of lead as trim ballast, and 10,000 pounds of water ballast, and 3000 pounds of personal stuff, you end up around 55,000 pounds for a no cargo condition. That would let you carry about 30,000 pounds of cargo by dumping tanks and letting draft increase by 1'. Designing a boat for that range in load isn't nearly as tricky as for greater load ratios as long as it is fairly dense and can be packed efficiently. And even at 3'6" draft no cargo, 4'6" in full load, you can do better than a flat bottom. File bottom sharpies evolved for yacht duty and some very nice ones were built over the years.

I don't know anything about the Newhaven type but I will look into it

 

[Rurudyne]

I don't know anything about the Newhaven type but I will look into it

Random post....

Here's a picture of Munroe's Savanilla, a sailing flat bottom houseboat with a draft of only 30", IIRC.

http://merrick.library.miami.edu/cdm/ref/collection/asm0015/id/283

I do recall reading that, having no motor, she was often towed rather than sailed (my guess due to crew requirements).

 

[Angélique]

I'm looking for a large steel sharpie type design in the 70 lwl no more than 80 loa draft 3-4 ft. Tom Colvin did a few however since his passing in 2014 his plans seem to no longer be available. She would be used as a full time live aboard and possibly transporting cargo. Can you guys recommend someone who would like to design this at a reasonable price or somewhere to find similar plans ?

-

On page 12 of the Hogfish Maximus thread there's some info and links about the above pictured boats.

Tom Colvin's website is back online now, so maybe there's someone who answers e-mails about availability of the plans, please let us know.

 

[Angélique]

Below post #244 from the Hogfish Maximus thread . . .

Don't know if this has been posted. A schonker, flat bottomed, internally ballasted.

The above Pierius Magnus* is not a sharpie but otherwise she seems to fit your requirements, that is if stretched to the desired length and maybe build with a centerboard.

I wonder though why there's no rocker and if she could use some . . .

* Named after the Frisian rebel leader Pier Gerlofs Donia, aka ‘‘Grutte Pier’’ in Frisian, which means ‘‘Big Pier’’ in English, and ‘‘Pierius Magnus’’ in Latin.

Some info about the boat Pierius Magnus --- Link 1 --- Link 2 ^{(kinda translation)} --- Link 3 ^{(kinda translation)} --- Link 4 --- Link 5 ---

Link 1 is in English, link 2 & 3 are in Dutch, link 4 & 5 are videos on YouTube in English.

 

[Schooner Guy]

Below post 244 from the Hogfish Maximus thread . . .


The above Pierius Magnus* is not a sharpie but otherwise she seems to fit your needs, that is if stretched to the desired length and maybe build with a centerboard.

I wonder though why there's no rocker and if she could use some . . .

* Named after the Frisian rebel Pier Gerlofs Donia, aka ‘‘Grutte Pier’’ in the Frisian language, which means ‘‘Big Pier’’ in English, and ‘‘Pierius Magnus’’ in Latin.

Some info about the boat Pierius Magnus -- Link 1 -- Link 2 -- Link 3 -- Link 4 -- Link 5 --

Link 2 & 3 are in Dutch. Link 4 & 5 are videos on YouTube.

Wouldn't the rocker shaped bottom of the sharpie have better performance in rough weather than a completely flat bottom

 

[Schooner Guy]

On page 12 of the Hogfish Maximus thread there's some info and links about the above pictured boats.

Tom Colvin's website is back online now, so maybe there's someone who answers e-mails about availability of the plans, please let us know.

Turns out the green hull soundwaters is not a colvin design.... I emailed the website a few weeks ago and have not received a response and I have had no results in trying to find a way to contact his children

 

[Schooner Guy]

Random post....

Here's a picture of Munroe's Savanilla, a sailing flat bottom houseboat with a draft of only 30", IIRC.

http://merrick.library.miami.edu/cdm/ref/collection/asm0015/id/283

I do recall reading that, having no motor, she was often towed rather than sailed (my guess due to crew requirements).

That's a hell of a houseboat..... I was trying to keep from designing a boat from scratch however it looks like I will have to.... Its a shame that when some of these great navel architects pass away that there life's work just disappears so to speak

 

[Rurudyne]

That's a hell of a houseboat..... I was trying to keep from designing a boat from scratch however it looks like I will have to.... Its a shame that when some of these great navel architects pass away that there life's work just disappears so to speak

Well, if you can find a copy of Houseboats and Houseboating, 1905, the plans for Savanilla have survived ... unlike too many of the Commodore's other work from what I've read.

But I believe she was for sheltered waters, though I recall reading that she exceeded Munroe's expectations.

That said, there are good NAs still and what they charge for custom work will probably be minor compared to construction. The hull design and construction isn't really the hard part, there are scantlings rules that are easy to apply like those by Gerr, so much as the interior arrangement seems to be the real bug-a-boo, and of course the plumbing.

 

[Angélique]

Wouldn't the rocker shaped bottom of the sharpie have better performance in rough weather than a completely flat bottom

Yes, I think so too. From the just wild idea of the initiators brought to live in this boat, and the speed of the build told in the videos, to me Pierius Magnus' longitudinal flat bottom looks like a mistake they made for the maybe expected ease and speed of building and underestimating the consequences of this choice.