1989 225hp Johnson Fuel Numbers

[wavelength]

We'll you guys got me thinking again... First high water alarm's and now fuel flow gauge's. I installed a LMF-200 fuel flow with paddle wheel for speed since my plotter does not speak NEMA 2000. I had been running the Johnrude around 3800rpm doing 21 to 22 knots and it felt pretty good trimmed and tabs set.

I've made two short grouper trolling trips and found that at 3800rpm I'm getting 1.5 to 1.6 miles per gallon. However at 4300rpm I'm doing 27 to 28 knots and getting 2.0 miles per gallon! Watch out I'm going faster burning less fuel grouper beware!!!!!!!

[eggsuckindog]

Actually I bet the boat is getting higher in the water, starting to climb up the deadrise at the faster speed. I know my boat feels much lighter and more nimbel at 3800 than it does at 3300. Your boat is heavier with a 225 than my MA with 200 so that 3800 is about 28/29 for me.

[ScottM]

Glad to hear those numbers are that good. I've got a '89 on my 23' Seabird and wondered what the fuel burn was. I bought a Navman 2100 a couple years ago but never installed it. At 4300rpm, my boat is also running 27 knots.

[Fr. Frank]

I have a 23' Tsunami, '88 225 Johnson w/new powerhead. I cruise at 4200 rpm, 28 statute mph, at 1.9 - 2.0 mpg calculated.

My 20' Seafari, '91 150 Merc, reman'd in '02, cruises at 4300 rpm, 35 statute mph, 9.9 to 11.0 gph on the Navman 2100, or 3.2 - 3.5 mpg depending on sea conditions and air temp/humidity.

Now Wide Open Throttle produces 51 statute mph at 6150 rpm, burning 18.8 - 19.4 gph, or 2.6 - 2.7 mpg.

Here's the mindblower: If I drop back to 3500 rpms (minimum planing speed in a chop), my speed falls all the way back to 23 mph, but fuel flow is 9.6 gph, or 2.4 mpg. I get better fuel economy at WOT than at 3600 rpms, largely, I believe, because of the greatly reduced wetted surface.

But a friend in Juno Beach, Larry, has a '74 Seafari w/ 1994 Mercruiser 140hp. He burns 7.75 - 8.0 gph turning 3800 rpm at 34 mph, or 4.25 to 4.4 mpg.

What kind of mileage are you guys with 4S outboards getting?

[Bushwacker]

Fr. Frank - I used to work with Larry! 2 different Seafari/140 Mercruiser rigs have made trips to the Abaco's with me, cruising at 20 kts (22-23mph) at about 5" vacuum with typical Bahama load (2 wks worth of beer & gear); both averaged around 5 mpg. This is pretty consistent with Seafari test that Boating Magazine did with Carl Moesly (11/69) - it's optimum cruise mph/mpg with a light load was 19/5.3 to 26.5/5.0. The same test showed running angle/mph changing from 2.5 deg/19 to .75 deg/25 mph to .5 deg/30+. Seems like the "sweet spot" for this hull is 20-25 mph, probably due to min wetted surface and most efficient running angle. I used to average 2.8 mpg on same trip running a 1975 Evinrude 115 (90 hp @ prop). Current E-tec set-up runs 5.2-5.3 mpg at 23-25 mph, based on I-command tach/flowmeter & gps spedo, with full fuel, bimini top up, 1 person on board.