Pounds of Thrust = Hsp

How many pounds of thrust is equal to 1 hsp ?

Who cares?
Too technical for me, but it wasn’t that long ago that Minnkota had a couple trolling motors out that were horse power rated. I think they were 3hsp and 5hsp.

http://www.onlineconversion.com

Click on the power section.

Whahhhh????

Can someone try right-clicking on the link to ‘open in new window’ and see if the menu pops up for them??

I get nothing! Not just that one, but any of the linkable text does not “right-click menu”

Allegdly, I have heard 17lb thrust ~ 1hp. You can’t make a perfect comparison, but this should suffice.

101# of thrust is about 2hp.

Actually 1 Hp is equal to 550 ft-lb of work per second.

Work is actually force x distance.

To find the hp from a known force or thrust value

you would have to make some pretty wild assumptions about

the distance per second component (speed).

Too many variables to use a speed value in this calc.

An easier way is to use the motor nameplate data,

to figure the brake horsepower.

For a single phase electric motor (ie trolling motors)

hp= current draw x voltage x efficiency x power factor/746

Minn kota states for their 74# thrust model

a max amp draw of 45 amps at 24volts.

Lets assume a 85% motor/system efficiency

and a .9 power factor (typical value).

The 746 is because there are 746 watts in 1hp.

hp= 45 x 24 x .85 x .9/746 = 1.11hp for the 74#unit

doing the same thing with 40#unit

40amp max, 12volt

40 x 12 x .85 x .9/746 = 0.49hp for the 40# unit

This formula can be verified at

http://www.bacharach-training.com/norm/electric.htm

This sure would be alot easier if the right-clicks were enabled.

Just have to use left-clicks on links for now till they get it fixed.

As far opening a page on a different window,

check out mozilla to use as a browser. It has whats called tabbed browsing which is great.

Once you see and use tabbed browsing, you’ll never want to be without it.

Actually, try using the short cut keys for functions like copy / paste. Highlight text by dragging with your left click. Then…

Control + C = Copy
Control + V = Paste

The controls we have in place do not come into play and excellent posts chock full of info, like the one you just made, go a heck of a lot quicker.

Hope this helps… if only a little.

Thanks for the tip.
I would prefer to compose posts like that off-line.

Very understandable. Lots of people tell me they use a text editor to compose a post, checking spelling & punctuation in their program of choice, and then posting the final product.

What we need here is a built in editor and spell checker!

The spell checker would be OK,
But alot of folks, like me are still on dial-up
so composing long things on-line is kind of a waste of
on-line time.

Now that I look incredibly stupid , take a look at this link. It should make your head spin.

http://www.walleyecentral.com/dc/dcboard.php?az=show_topic&forum=3&topic_id=222852&mesg_id=222852&listing_type=search

Nub, I wasn’t trying to put anybody down or make them feel bad.
I just wanted to try and explain it so folks could understand it.
That link pretty much substantiates what I said
except he didn’t take into account power factor.
Maybe my explanation was too visually descriptive.
Hopefully I just got the idea out as painlessly as possible.

Can I just ask 1 last harmless question, and then I will rest ??

Someone stated that a 101lb trolling motor would roughly = 2hp. Ok. So a 65lb MK would be a little over 1hp. Now if I was to put a 1hp motor on the back of say, a 18′ TS, I doubt it would do anywhere near the work a 65lb Mk would do. I know on my boat, that troller moved my boat pretty quickly. So something isn’t adding up.

The 1hp MK is derived from nameplate date and is just looking at the capability of the electric motor.

The 1hp OB is derived from the powerhead’s data,

and doesn’t take into account the gearing and drive train losses.

If you had 2 boats,

one with the MK and one with the OB,

same prop on each motor,

batteries removed from boat with the OB to equalize weight,

and some kind of brake on the MK to simulate the OB’s drivetrain loss’s.

I bet the boats would have real similar performance.