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ContinuousWave: Whaler Performance
Need Prop Suggestions
|Author||Topic: Need Prop Suggestions|
posted 10-22-2002 06:19 PM ET (US)
Have one more question, Im thinking about changing the pitch on the SS prop, the pitch is 17 and it was on a 25 mako, since Im putting on the 22 outrage, which is a lot lighter, I think I'd be better off with a 19 pitch, Im just thinking that the 17 would put me at about 6500 RPM when I should be at 5400 =-5500 what do you think?
posted 10-22-2002 07:33 PM ET (US)
Find out from the MFG what rpm should the engine be turning at WOT.
Then prop to get in the upper part of the range.
posted 10-22-2002 08:58 PM ET (US)
Forgot to say that the engine's a 250hp merc
posted 10-23-2002 08:55 AM ET (US)
Rule of thumb is for every 2" of pitch you should drop 400 rpm. So if you are at 6k, a 19" will bring you close to 5600. Put it on and go from there.
posted 10-23-2002 10:15 AM ET (US)
Well I don't have a big merc but on my old 235 johnson she swings a 19 pitch freshly done aluminium, I should be swinging a higher pitch. But I like the midrange punch and the get up and go with full fuel and four people onboard and two tube being pulled. Currently (and yes the tach is correct) she turns a touch over 6500. Yes its to high but the hole shot is great. I'm getting tired of premix but until I figure out which wiz kid engine to put on next, I'll keep the stinky one. If you have the 17 run it and see what it does, then look at your gearing and your rpm and then judge what to get from there. Make a base line first then change so you have something to relate to. If not start with a 19, maybe barrow one from friend/dealer/propshop? search your buddies and pals club. good luck
posted 10-23-2002 10:17 AM ET (US)
What is that on? A 19" swinging 6500? Your max rpm is 5500 so you theoretically should be swinging a 23-25" prop....still think that tach is accurate?
posted 10-23-2002 11:10 AM ET (US)
22' OR w/225 Yam, 1 hole down, 19 yam SS prop, 4900-5000 wot.....the 17 turned 5700-5800...that was too much in my opinion. The boat runs great, 2+ mpg, and cruises at 3000-3100 going 28-30 mph
posted 10-23-2002 11:15 AM ET (US)
1980 22 revenge owned since 1987 and yes the tach is correct at least according to the machanic, so who am I to argue with the guy that owns the shop? I questioned it once, he brought out his hand held gadgit, started it up they were as close as a needle and his digital could get within reality, so I shut up. Anyway that is running with just my wife and I and well under a quater tank of fuel 77 total so 15 gals? maybe less. Is it good for the engine no..but shes comfortable at creusing speed. But,once in a while its kind of like using war time only emergency power, when you forget to put the potty in front your close to home and the wife has to go.. or when a drunk in a checkmate thinks he wants to play with a slow fishing boat, she doesn't go up there often but when she does what a great howl, I do like the sound of high rpm's(profile). Maybe I'll try a 21 or 23 next summer but the wife really wants to get rid of old stinky (Hope she ment the engine).
an appology for the english majors:
posted 10-23-2002 11:25 AM ET (US)
opps "cruise" told ya C for complete
also she cuises at 3800-4000 the engine gets..quite-comfortable at that rpm don't know the speed but checked the gph about 13 never really mattered around here, I can alway find a place to get gas.
posted 10-23-2002 11:45 AM ET (US)
try not to run it over 6k, the cylinder walls will delaminate:)
posted 10-23-2002 07:16 PM ET (US)
A Merc 250hp EFI 3.0 liter is going to fly on an Outrage 22. A 21" Merc Mirage carries a load of 3000-4700lbs, and shows 48-60 MPH. I'd guess closer to 60. You might also want to consider a 4 bladed Bravo I in 22" pitch. These need to be run elevated about 1 1/2".
A 23" pitch prop carries a load range of 2400-3700lbs, and shows a speed range of 53-66mph. It's entirely possible you may need a 22" or 23" pitch prop.
If you are interested in speed, my first choice would be the 22" Bravo I, assuming the boat is not heavily loaded. Engine should be mounted in the middle of the 5 holes in any situation.
A 19" pitch prop will be too low. In any case, don't use a conventional elephant ear SS prop for a rig that will run over 40mph.
I have heard that the Merc 250 EFI really puts out about 265 prop HP.
|John from Madison CT||
posted 10-23-2002 07:34 PM ET (US)
I would expect the Merc 250EFI to do about 50mph assuming that this is a non Whaler Drive model and the boat has no tee top.
A 21" pitch would probably do you right.
posted 10-23-2002 08:43 PM ET (US)
Louie Kokinis has indicated that his heavier 22 Guardian, with Merc 225 EFI & 4 stroke 15 Hp trolling motor, does about 53.
posted 10-23-2002 11:10 PM ET (US)
John- Hey, run the 17 pitch-- see what happens- you've got a tach. Repitch to suit your purposes. Sort of like seasoning a nice piece of pompano. .03 David
posted 10-24-2002 12:06 AM ET (US)
IHG, the engine manufacturs are allowed 10% more hp, then advertized, so the 250 is 275,....or better.
For instance, my 200 FICHT is putting out 222 hp at the prop, 2 hp over which is allowed.
OMC was very famous for advertizing say 150 hp, when in fact they were allowed 10% = 15 hp = 165 hp, but were really like 170 - 175 hp with a 150 rating.
A friend of mine races mercs, he calls his 250 hp a 280 hp [ acually is 280 hp ] with a quickie lower unit, his 16 ft [ looks like a custom bass boat ] made of i think kelvar, runs 116 mph.
Dry weight of the boat is, 800 lbs.
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