Trojan Boat Forum

Posted: **Fri Mar 30, 2012 8:09 pm**

will crusing at low rpm's save on fuel

Posted: **Fri Mar 30, 2012 8:15 pm**

My experience is that it will definitely save on fuel, but you obviously sacrifice time. If you are like me and love to be on the water and the trip is a large part of the goal, then it's a good trade-off. If the destination is the goal and time is of the essence, then it is a bad deal.

Posted: **Fri Mar 30, 2012 8:19 pm**

Only if you are running at or below 'hull speed' (= 1.34 x square root(water line length)). That is as fast as you can push through water without the boat trying to climb on top of it (ie plane). Hull speed is the fastest you can go without starting to burn power trying to also lift.

I don't have the number near me, but for the F32 waterline length is about 28' I think. So about 7 knots (around 1500 rpm probably) is going to be the fastest you can go for the least fuel.

Posted: **Fri Mar 30, 2012 9:07 pm**

captainmaniac wrote:Only if you are running at or below 'hull speed' (= 1.34 x square root(water line length)). That is as fast as you can push through water without the boat trying to climb on top of it (ie plane). Hull speed is the fastest you can go without starting to burn power trying to also lift.

I don't have the number near me, but for the F32 waterline length is about 28' I think. So about 7 knots (around 1500 rpm probably) is going to be the fastest you can go for the least fuel.

Good point and thanks for bringing it up.

Posted: **Fri Mar 30, 2012 10:19 pm**

on the other hand, and on a more practical note, running your boat the way it was designed and intended with an understanding of it's optimum cruising speed/RPM and using trim tabs you can enjoy reasonable fuel consumption and get to where you are going. After all, it is a POWER boat.

Posted: **Fri Mar 30, 2012 11:00 pm**

You Run that F32 a hull speed you will save a lot . I maybe doing the same on my F36 .

Posted: **Sat Mar 31, 2012 7:57 am**

I have ran my F32 both at haul speed and on plane for long trips. I get almost double the fuel economy at haul speed. That is a whopping 2.2 nautical miles per gallon vs the 1.0 nautical mile per gallon on plane.

Posted: **Sat Mar 31, 2012 8:12 am**

We run at hull speed alot 8 knots, most when we're just doing lazy trips...you know trips with no real place to go...but if we have to be at way point on set time the speed is set for that...but no faster than 17 knot that's the sweet spot...for 1 to 1.

Posted: **Sat Mar 31, 2012 8:23 am**

Ahh, yes, that's what i'm talking about,..the "sweet spot".

Posted: **Sat Mar 31, 2012 8:41 am**

thanks everyone for the most part I think that we will be running @ hull speed( think some 1 said 7 knots) holding that massive fuel bill for when we need it. the main goal is to have a good time !!!!

Posted: **Sat Mar 31, 2012 8:59 am**

I get about the same numbers as Alexander 7 knots and 16 knots as my sweet spots.

Posted: **Sat Mar 31, 2012 9:08 am**

My "Sweetie" is 16-18

Ron

Posted: **Sat Mar 31, 2012 9:12 am**

What does running a gas engine at 1000-1500 RPMs for a extended time do to the carbs, and spark plugs?

Posted: **Sat Mar 31, 2012 9:15 am**

I have put alot of thought into this subject. I purchased and repowered my single screw F30 express last fall and have not launched yet. My solution was to buy a Floscan.

http://www.gandermountain.com/modperl/p ... SHOP_94165
The hour meter is a nice bonus for keeping track of use on the new engine.

Posted: **Sat Mar 31, 2012 9:53 am**

kevin im thinking if your engines are tuned and running properly there should be no problem running at 1500 plus rpm. 1000 will barely be above idle. not sure but i think your year and engine type should be throttle body fuel injected. they look like carbs with spark arrestors on.i was told they are a great fool proof system if thats what u actually have.

Trojan Boat Forum

run it like a trawler ????

run it like a trawler ????