Trojan Boat Forum

Looking for the cruising speed for a F-32 w/233hp mercruisers, and at what RPM?

I have only ran my F32 for a couple hours now, but here are the couple of numbers I observed:

15 kts @ 2700 rpm
20 kts @ 3000 rpm

Sorry haven't had much chance to do anymore speed/rpm noting.

Didn't have the Mercs but had chrysler 225/240 hp 1.5 gears. Best cruise for my boat was 17 knots @ around 3000 rpm. My boat was heavy and may have been a little slower than some. Anything above that tends to flirt with 4 BBL operation.

Thanks for the info!!

I've been wanting to do a rpm/speed test on my F32. So last time I took the boat out here are the numbers I got. Tests were done with boat trimmed at all times. Cross wind of 10 kts on Starboard, Fuel about 1/3 tanks, waves calm and speeds off GPS, no current.

RPM Speed Kts
800 4.6
1000 6.0
1200 6.9
1400 7.5
1600 8.2
1800 8.7
2000 9.8
2200 11.5
2400 14.1
2600 16.2
2800 17.8
3000 20.4
3200 21.6
3400 23.0

I didn't run it past 3400 rpm due to still breaking in my rebuilt engines. The boat was on plane at about 2200-2300 rpm. Hope that helps.

ScurvyDog, What engines do you have?

Willie, I have the 305 cid Mercruiser 228 hp engines with 16 / 15 three blade props

Sorry about another post on speed and prop size, at least I opened this post back up so I don't add to the million posts on prop size.

I could not believe the numbers I was getting on my f32 with old tired crusader 318s this evening. I have 16x15 nibral super cup props, front fuel tanks are empty with only 1/4 full rear tanks, clean bottom, removed generator, ect.

14-16 knots on plane, 1500-1800 rpm
18-20 knots 2200-2300rpm
26-27knots 3200-3300 rpm (WOT) cant go no more. Actually it was 30-31mph on the GPS.

So one would think the props are way to big for this boat, but they are only 16x15 (I think thats stock size? )

I cant be specific (bad memory) but the trannies are velvet drives 1:1 or 1:51 I dunno here.....

So the question is are my engines too weak and should she run faster?? NOT!!!! But could the NIBRAL really make that much difference. With my girl there is no possible way I can hit 4400rpm with what I am running?

But on the flip side I like cruising at 17 knots running around 2000rpm.

One last thought, maybe this is why I used to only be able to get 1.5 gallon per mile at 18-20 knots?

Mac if your tachs are right your ov er loading your engines badly .

to turn those wheels you would need 1.5 to 1 gears to get near the correct rpm range . if you had 1 to 1 your boat would be a dog getting on plane with those wheels . I am betting your tachs are off .

1.5 MPG at 18-20 knots ? sounds high , I bet moat are getting closer to 1
with the gas engines .

Something doesn't sound right...18-20 Kts at 2200-2300 rpm??

I need to be at 2900-3000 to turn those numbers with good seas. Are you sure your tachs are correct? I'm running 16X16 props as well, clean everything.

Yeah- somethings not right.

Paul- he said 1.5 GALLONS per Mile- not Miles per Gallon so his figure fuel figure seems reasonable.

But- Crusader never made a 318. The 318 was a Chrysler engine that was available with 225 HP or a slightly hotter 240HP version.

Ther only thing that makes sense is either:

The tachs are way off OR
The gears are 1:1 and the engines are way overloaded.

Paul,
Mac stated 1.5 gallons per mile.... Not 1.5 Miles per gallon.
I would still be happy with that myself in my boat. At cruise, 2250 rpm, I am using 2 gallons per mile!
I have owned a couple of F series boats and at cruise I would get about .8 mpg.

I never really thought the tachs could be the culprit but it makes sense now. Because all in all the boat pops up on plane pretty good and seems to run smooth with throttle response all the way up to WOT and putting the boat at 26-27 knots with 16x15 props. So at those numbers with the rpm WOT being 4300 the boat would top out at 35 knots I dont think so.....

Also, yes the engines are Chrysler 318 (225hp) with the factory electronic ignition and Carter AFB carbs. And I am pretty sure the trannies are 1.5:1 with the fuel consumption at 1.5 gal per mile or .7mpg depending on how you look at it. (sorry didn't mean to sound like a dumb nut). But this was from trips I made in her years ago fully loaded, not like the hot rod she is this season.

I dont know if it could have caused something but I did disconnect the engine synchronizers (both from the coil connections) ? AND the Starboard tach flickers at WOT (jumps back or drops out).

Sounds like I have a investigative project this weekend.

Thanks for the feed back guys, this place is priceless......

Those numbers seem pretty high, I have to run 3100 just to get 16.5/17Knts

Looking at these #s on the F32 the Internationals must be pigs. My 10 meter @ 2200 =12mph; 2800 = 14 mph; 3000 = 16 mph with a clean bottom,running gears, full fuel and water. Max rpms is 4100 @ 22 mph.

Fuel consumption is something I don't like to look at. If I every get my Wellcraft 2800 Coastal sold (1 year on market), Yanmars are going in.