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stubones99 said:
Anyone with a 50+ ton full displacement vessel will tell you that there is hardly any difference in fuel economy or speed between light load and full load.

On Semi-displacement / planing hulls, weight is critical, since you have to transition from displacement to on top of the water and it takes horsepower to do that.
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"hardley any difference" in a boats gros weight means hardly any difference on any size boat. It's basically directly porportional.
 
Here's an interesting fishing boat in Alaska. Looks like she's ready for quite big water. Must be one of those guys that fishes 20 miles offshore. Visibility out those pilothouse ports must be fairly limited but that's what my dad had on his Navy "baby freighter".
 

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Nice little salmon troller Eric. Not much view out the portholes but those portholes are likely to survive repeated breaking green water incidents. Only view he cares about is filling that fish hold.
 
I'm thinking he chose those ports because they were available at the time. Served the purpose. Nothing more, nothing less. "Get-er-done" type of thing. win-win on all fronts. +1, why not?
 
manyboats said:
No .. Talking about full displacement boats/hulls.

When I think of how much power power is required to drive a FD hull I'm think'in how much hp per ton of disp will I need. Willy (my boat) has 5 and 3.5 to 4.5 is about right. Trawlers are largely SD boats and I'm quite sure they are not linear in this regard.
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Exactly, purely proportional for FD hulls as long as the hydrodynamics don't change, like when the transom starts getting wet etc.
Wild South is light, but still pure displacement. It is a matter of hull shape first and foremost, it really relates to the way the hull works.

A quantity of interest when choosing a boat is the length/displacement (L/D^0.33) ratio if speed (and economy at speed) is any consideration. The rise in the resistance curve is softened/deferred, at least initially, when the L/D ratio is high enough.
It is nice to get at least 5.5 or so, preferably 6+. The best length to use in the calculation is the wetted length of the hull at speed. Displacement is volume in cubic metres.

SD hulls lose their top end a lot more quickly when loaded and a lot of the time they are not as good at lower speeds. I have come to think that trying to generate hydrodynamic lift is more a mistake than anything else, unless the objective is planing speeds. Who says lift says induced drag and the penalty is very significant.
 
A full displacement boat will go cheapest at about the SQ rt of the LWL.

As it takes 2-3 HP per ton (2240lbs) dumping 10% of a 50,000 lb boat is just over 2 tons.

With a diesel creating at best 16hp per gallon the removal of a 4 to 6 hp requirement is not measurable , unless on a long ocean passage where 1/4 GPH might get noticed in 50 or 100 hours of steady motoring..

The advantage of the true full displacement hull is constant ,
hull shaped for the task, no dragging transom, proper sized engine and gearing.

6K or 7K is where most folks seem to travel when its a 500, 1,000= miles of trip.
 
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FF said:
A full displacement boat will go cheapest at about the SQ rt of the LWL.

As it takes 2-3 HP per ton (2240lbs) dumping 10% of a 50,000 lb boat is just over 2 tons.

With a diesel creating at best 16hp per gallon the removal of a 4 to 6 hp requirement is not measurable , unless on a long ocean passage where 1/4 GPH might get noticed in 50 or 100 hours of steady motoring..

The advantage of the true full displacement hull is constant ,
hull shaped for the task, no dragging transom, proper sized engine and gearing.

6K or 7K is where most folks seem to travel when its a 500, 1,000= miles of trip.
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Yes, but the question of the most economical speed is a little more involved. In terms of hull, L/D has a lot to do with it, the canned formula is only going to be relevant around a given value of L/D (not a very favourable one, I would add).

Because power requirements always increase faster than speed, we could naively offer that slower must be better. In fact it is not, because the engine has a fixed fuel consumption just to "run itself" for a start and there is a point where slow speed becomes more wasteful. Low load makes engines less efficient.

Same about the propeller, its efficiency at low thrust is poor: too much torque expended to overcome friction over the blades without producing enough useful work. This is also why a larger propeller is not automatically better for cruising - well on the contrary. It needs enough pitch to get good efficiency at design cruising speed and the ability to slip instead of overloading closer to the top and this creates an optimum combination of diameter and pitch.

Lighter pure displacement boats are in fact very different in many ways and they need to be analysed specifically.
 
Those steel ships sure look cool, but I can't imagine having to keep up with all the painting and rust chasing.

Plus, I don't see any stabilizers on the 2005 boat. Wouldn't she wallow around in beam seas?
 
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Stabilizers are one thing they did leave off that boat. It has at least one of everything else though. and new paint, so that's a problem for the future.
 
Art,
Your'e the Tollycraft expert ... Where's the rest of the 2nd deck wheelhouse?
Looks funny w that part missing.
 
manyboats said:
Art,
Your'e the Tollycraft expert ... Where's the rest of the 2nd deck wheelhouse?
Looks funny w that part missing.
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Gee Eric - Thanks for the compliment.

I've not a clue. Any expertise I may have about Tolly's is up and including to the 48'er production models. Above that length, far as I know, and although there were definite similarities in the big-ones, each of the longer than 48' Tolly was a custom designed craft.
 
stubones99 said:
Stabilizers are one thing they did leave off that boat. It has at least one of everything else though. and new paint, so that's a problem for the future.
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Or maybe due to the hard chine design and weight it's pretty stable?
 
stubones99 said:
I think what you're talking about is Semi-displacement or planing hull boats. A displacement hull boat efficiency changes only slightly based on weight. Most true displacement hull boats are about as efficient with full fuel as they are nearly empty.
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The hull form doesn't matter, in any hull adding weight will increase resistance, frictional drag and wavemaking. It takes accurate tools to measure, but it's definitely there.
 
Art said:
Gee Eric - Thanks for the compliment.

I've not a clue. Any expertise I may have about Tolly's is up and including to the 48'er production models. Above that length, far as I know, and although there were definite similarities in the big-ones, each of the longer than 48' Tolly was a custom designed craft.
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Hey Art,
Not crititicizing you one bit. Just the design of that boat. However if I had seen the huge top cabin that was probably once there I would be saying the assumed mod was a step in the right direction. Not very pleasing to the eye as it definitely looks cut off.
 
manyboats said:
Hey Art,
Not crititicizing you one bit. Just the design of that boat. However if I had seen the huge top cabin that was probably once there I would be saying the assumed mod was a step in the right direction. Not very pleasing to the eye as it definitely looks cut off.
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Agree. Unless they guy is like me and has difficulty finishing his projects, it does look incomplete. Still, this Photoshop mock-up looks more balanced.
 

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cardude01 said:
Or maybe due to the hard chine design and weight it's pretty stable?
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Are you referring to stability or to comfortable motion?

Like most ocean-capable powerboats, if the deckhouse/ports/doors all remain intact then the boat is pretty much self-righting, especially in large waves.

Regarding motion - chine and weight may provide a comfortable roll but there is a natural period and motion. If you want to reduce the "natural" roll then you need stabilization of some sort.

Probably better to hit the boatdesign.net forum for more info on this subject.
 
Yup .....
I'll bet that's the way it was before sombody decided they wanted more air.

Thank you Larry. You're really getting good at that!,.
 
Interesting boat - Troller

I came across this picture of what I think is a troller built in either Alaska or Washington. Has anyone seen the actual boat or have any information on it? Is it a troller?
 
Greetings,
Welcome aboard. I think you have to have a minimum number of posts before you can add pictures. As a result, NOBODY can see what picture you may have attempted to post so the answer to your questions...Nope and don't know.
 
Yacht Bystander of Man

I met her 2 weeks ago in Villefranche Sur Mer, close to Nice, South of France. Stunning woody yacht.

http://www.camperandnicholsons.com/pdf-brochure/bystander-of-man-1111.pdf

"Built in 1934 by British Shipyard Camper & Nicholsons, this charming 25m (82’) Gentleman’s Yacht was commissioned by W. Stephenson to follow his famous J Class racing yacht Veshelda in regattas throughout the world".
 

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Skeetsdad said:
I came across this picture of what I think is a troller built in either Alaska or Washington. Has anyone seen the actual boat or have any information on it? Is it a troller?
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http://www.trawlerforum.com/forums/s22/set-up-your-account-|-help-tips-etc-5739.html

Go to the link above and read post number 6 and follow the directions for posting pictures. You will get a message that your post is being reviewed for approval and it will show up as soon as a site team member approves it. After 10 posts that goes away.
 
MurrayM said:
Wake? What wake? (48 second mark of "Summer 2015" video)

VIDEOS | The Banshee. 58' North Sea Trawler
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I did take notice of the big wake in the video... but that could or been caused by the skipper wanting to show off for the camera.. look at the stern wake in the other video.. it looks really flat.. who knows.

A lot of boat that looks pretty well done for the money.. the bridge dash/ helm needs some redesign but the E.R. looks very well laid out. Typical in some home built boats.. the builder spends a lot of time laying out the engineering spaces and does a less than stellar job on the aesthetics of the woodwork.

HOLLYWOOD
 
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