Atkin's Happy Clam's propeller

[gonzo]

Interruption means that there is a period with "clean flow" ( I assume you mean laminar) and turbulent. In fact there is always turbulent flow. The variation of pressure on the blades, also called loading, causes vibration when it is cyclical.

 

[rangebowdrie]

Yes, but that need not be a result of the imbalance of the rotating mass.

 

[Dave G 9N]

So the flywheel can do a lot of things in addition to storing enough energy to keep a low speed single cylinder turning slowly under loads. And is the conclusion that the flywheel's inertia is needed to keep a large prop swinging slowly with a low power single cylinder engine? And it has been said above that a 6 horse Palmer should be capable of turning a 6x10 prop.

I may build the boat. I will not try to locate an old Palmer.

The engine pictured in the link is shown running about 30 rpm about 10 minutes in. It obviously needs some rotating mass to run smoothly at the speed. Flywheels can also damp vibration, reduce variations in engine speed, help balance the engine and so on, but all of that is just taking advantage of a rotating mass without which the engine might not run at all. Dampers and counter shafts can do all of these things, but only a flywheel can keep the thing running between the first power stroke and the second.

 

[gonzo]

Yes, but that need not be a result of the imbalance of the rotating mass.

On an engine that rotates, the vibration is caused by imbalance of weight, forces, or both. Dampers and counterbalances help reduce vibrations.

 

[gonzo]

And is the conclusion that the flywheel's inertia is needed to keep a large prop swinging slowly with a low power single cylinder engine?

Not at all. You need an engine that produces the power required. The torque can be adjusted with gearing.

 

[fallguy]

Not at all. You need an engine that produces the power required. The torque can be adjusted with gearing.

There was no gearbox for the engine, afaik. So they can only adjust at the shafts. Am I misunderstanding you here?

 

[gonzo]

Is it a "start in gear" installation?

 

[rangebowdrie]

I may build the boat. I will not try to locate an old Palmer.

So, I went to the site and looked at the design and the pics of it.
Oh yeah, instantly recognizable as an Atkin design.
The speeds? perhaps Bill was a bit optimistic, not a big deal.
Nice hull form for intended use, he kept good beam running aft, didn't try to pinch it in.
If you do build her, I would offer one suggestion.
In the pic that shows the aft/starboard quarter, that last frame that joins transom to hull sides?
I would "beef" it up somewhat to give more faying surface for the side planks, it'll not only add some strength to a place that's prone to troubles, but it'll allow the plank fasteners to not be so close to the ends of the planks, (always a good idea in wooden construction).
All in all, (like most of Bill's designs,) a decent boat that won't give you any grief.

 

[skaraborgcraft]

S

I may build the boat.

I got obsessed enough with his box keel boats to build a half size 13ft model to put to rest in my mind, the speed and power requirements.
Turned out to have a better speed for the power than some formulas suggested.

And the performance was had with smaller than ideal propellor disc sizes.

 

[fallguy]

Is it a "start in gear" installation?

No or yes and no. The earlier versions had optional clutches I read. Some of the later engines had reverse as well. So, point taken. They just didn’t have a transmission; per se.

 

[Dave G 9N]

The text says"Engine (Palmer Baby Husky with reverse gear and rope starter) $ 314.00" There must be a clutch. Prices have gone up a bit since 1950.

An air cooled small engine, say 12 hp with a v belt drive might work. 12 may be more than enough power, but the advertised hp is probably 20-30% higher than the continuous duty rating.

 

[gonzo]

If it has reverse, it has gears. The ratio can be chosen to match the engine to the propeller.

 

[Dave G 9N]

If it has reverse, it has gears. The ratio can be chosen to match the engine to the propeller.

Yes, but in 1950, Palmer probably offered the same number of gear ratios for the baby husky as Ford offered colors for the Model T. Any ratio you want, as long as it's 1:1.

Having exhausted my vast knowledge of marine transmissions, I will leave it to you to read this and explain it to us:

Of all the myriad mechanisms and devices that combine to push your boat through the water, none is more ignored and misunderstood than the marine transmission.

 

[gonzo]

Yes, but in 1950, Palmer probably offered the same number of gear ratios for the baby husky as Ford offered colors for the Model T. Any ratio you want, as long as it's 1:1.

Having exhausted my vast knowledge of marine transmissions, I will leave it to you to read this and explain it to us:Of all the myriad mechanisms and devices that combine to push your boat through the water, none is more ignored and misunderstood than the marine transmission.

It is the opinion of someone with little knowledge of mechanical systems.

 

[gonzo]

Yes, but in 1950, Palmer probably offered the same number of gear ratios for the baby husky as Ford offered colors for the Model T. Any ratio you want, as long as it's 1:1.

He is not limited to the factory installed gear ration, if it is in fact a 1:1, wherever you got that information from. There are any number of gear that can be bolted on to that engine.