Seastoke
Well-Known Member
Ok we have max speed and cruising speed ,why, as in a car we seem to thrash them whats the diference
Why cruising speed
- Thread starter Seastoke
- Start date
MrB
Well-Known Member
Fuel economy?
darryl_g
Member
Fuel economy & comfort
Barleycorn
Well-Known Member
Some of us, who buy their own diesel, drive their cars at cruising speed!
paul salliss
Well-Known Member
It's all about crew and comfort, we have been out all weekend ( final leg tomorrow) interesting sea conditions today, thank goodness we did not thrash, it's about the getting there , it can't be compared to cars, chalk and cheese, if the crew are happy then the atmosphere is relaxed and that's what it's all about it is not a sport it is leisure activity, if you want to thrash go power boat racing
rafiki_
Well-Known Member
How long do you drive your car at max power? Unless it is a Sinclair C5, then not very long! On a project a few years ago, we measured the power usage of a high performance C class car, over a full day it average 17% of full power, and this was driven aggressively. Generally you cruise at 15-20% in most average cars, which is considerably lower than in your boat, unless you are on the rivers.
omega2
Well-Known Member
Unless you have DPF fitted the a thrashing now and again is recommended. LOL
Latestarter1
Well-Known Member
Wow remind me to never take a lift in your car!
Say a typical 2 liter diesel saloon car which has 140 hp at rated speed of say 4,000 rpm. Typically car would be geared for around 135/140 mph at rated speed, engine is spinning just above peak torque which is say 2,000 rpm, therefore decent cruise 70/80 mph between 2,300 and 2,500 rpm and a road load of around 100 hp with a nice wedge of torque rise to cope with stiffening gradient.
I would struggle to run at a constant speed at 80 mph in cruise control uninterrupted for an hour let alone 135 mph. Even in cruise control engine load is constantly varying due to changing gradients. In a boat rated power is just that, pulling 80% plus load dependent on fouling, dependent on manufacturers rating conditions for half an hour to an hour.
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BruceK
Well-Known Member
As stated, even in my Land Rover which is pedestrian I am only feathering the throttle at motorway speeds. The engine is by no means loaded except to attain that initial speed and then break wind resistance. Not so in a boat where you have to break water resistance a much greater proposition.