HP to Weight Ratio

[Fireman431]

Anyone know the correct or industry standard of HP:weight? This came to while reading another thread and I just did some simple math:

Boat is 21,000 lbs. Engine(s) total HP is 620.
21,000 ? 620 = 1 HP per 33.87 lbs = 24.7mph WOT via GPS

How does everyones elses vessels compare? Omit the variables such as hull condition, elevation, tuning, etc. and figure boat weight/half tank fuel/average load.

I was just wondering how things truly stack up.

 

[NYBo]

Re: HP to Weight Ratio

About 19 pounds/HP

 

[tswiczko]

Re: HP to Weight Ratio

about 4500/270= 16.66

43 knotts (49mph)GPS

 

[wbc1957]

Re: HP to Weight Ratio

Weight at 2400 lbs. and HP at 185 equals 1 HP per 12.97 lbs. Yes, it does move pretty fast on the water....

 

[rallyart]

Re: HP to Weight Ratio

Sanger D215, 3200# with 330 hp. is close enough to 10:1 but you've got to add gear weight. 0-30 in under 5 seconds but its top speed is only 42

 

[26aftcab454]

Re: HP to Weight Ratio

7,000lb/300hp= 23.6lb per hp -- it will hit 40mph on a good day.

 

[Bass Buster One]

Re: HP to Weight Ratio

Sea Ray BR 17' w/ 3.0L Merc.: 1HP per 16.5#
Venture Bass Boat 18' w/ 150 Merc. OB: 1HP per 11.33#

 

[PBJT]

Re: HP to Weight Ratio

2008 Rinker 260 cruiser. 6700lbs (dry), 300 hp, 22.3lbs per hp. Hits 40.2 mph gps.

Pete

 

[Sharp Shooter]

Re: HP to Weight Ratio

1975 Biesemeyer sprint boat. 2,300 lbs/1,400 hp = 1 hp per 1.6 lbs Can any members top that one?

 

[dockwrecker]

Re: HP to Weight Ratio

Sanger D215, 3200# with 330 hp. is close enough to 10:1 but you've got to add gear weight. 0-30 in under 5 seconds but its top speed is only 42

What? you're 9.69 lbs per HP, I'm 17.38 loaded and I can pull 40 at 6000' elevation in a mid cabin cruiser. Something's amiss here!

 

[Fireman431]

Re: HP to Weight Ratio

Wow...after reading some of these I need to either put in bigger engines or get out the sawzall and get rid of the flybridge.

I guess mine was never really designed for speed, but the posted speeds for the boats above all seem in proportion with mine.

Thanks for the input.

 

[wire2]

Re: HP to Weight Ratio

19' Glastron SX190, ~2800#, 300+hp. Planes in 1 second, 58 mph.

 

[Ike-110722]

Re: HP to Weight Ratio

Actually the industry doesn't use lbs per hp as a method for determining hp for boats over 20 feet in length. Under 20 feet they use the USCG formulas. Above that there are various methods, probably the one most commonly used was developed by Dan Savistky and is appropriately called the Savitsky method. It is based on a variety of factors, length, waterline beam, resistance, amount of vee, weight and some other parameters. There are also calculators to get a rough estimate. Probably the one most commonly used is Crouch's speed calculator http://continuouswave.com/cgi-bin/crouchcalc.pl

Many small volume builders play it by ear. they know what has worked in the past so they use that and try it out. If it seems underpowered they go with something bigger. The old seat of the pants method.

For outboards most use the ABYC manueverability test to determine max safe horsepower, or the ISO collision avoidance test. Both are designed to limit HP to that which keeps the boat safe to do sudden maneuvers at full speed.

 

[LippCJ7]

Re: HP to Weight Ratio

I prefer 4lbs to every 1HP but until Boats get lighter or they start putting top fuel dragster motors in bowriders I don't think they will ever match my Super Bike!!!

 

[Sharp Shooter]

Re: HP to Weight Ratio

I prefer 4lbs to every 1HP but until Boats get lighter or they start putting top fuel dragster motors in bowriders I don't think they will ever match my Super Bike!!!

They have Top Fuel dragster motors in 18 foot hydroplanes. 7,000 hp in a 2,000 lb boat.

A 9 second crotch rocket is tame compared to 7 sec (or quicker) dragboat.

I have a frieind with a 1200 hp bow rider. It's pretty fast but too heavy to be really quick.

 

[H20Rat]

Re: HP to Weight Ratio

1450 pounds, 240 horse. 6 pounds riding on every horsey, trying to hold on for dear life!

 

[H20Rat]

Re: HP to Weight Ratio

I prefer 4lbs to every 1HP but until Boats get lighter or they start putting top fuel dragster motors in bowriders I don't think they will ever match my Super Bike!!!

the biggest seadoo jetskis are under 4 lb's to every horse.

 

[LippCJ7]

Re: HP to Weight Ratio

They have Top Fuel dragster motors in 18 foot hydroplanes. 7,000 hp in a 2,000 lb boat.

A 9 second crotch rocket is tame compared to 7 sec (or quicker) dragboat.

I have a frieind with a 1200 hp bow rider. It's pretty fast but too heavy to be really quick.

OH I KNOW!! I grew up around hot boats but the wife would divorce me if I tried one in my Crownline!! Something about her top flying off er I dunno we were doing 50 when we were discussing it

 

[LippCJ7]

Re: HP to Weight Ratio

the biggest seadoo jetskis are under 4 lb's to every horse.

I like the PWC's I just hate the constant maintenance of them, Maybe someday I can find someone to let me try one of those with the PROPER horsepower/weight ratio's!

 

[rallyart]

Re: HP to Weight Ratio

What? you're 9.69 lbs per HP, I'm 17.38 loaded and I can pull 40 at 6000' elevation in a mid cabin cruiser. Something's amiss here!

LOL
Nothing amiss. I have run 40 at 5000' but mine's an inboard built for making a smooth wake. Your's lifts the hull and has efficient running gear. Mine makes smooth water behind at any speed and corners on rails. You probably get better economy than me at full throttle but I probably get better economy at 25 mph.
Any mid cabin cruiser that can run 40 at your altitude is doing pretty well.