125 HP on my 1975 20' SF..Under powered ?

[Texascoastalfish]

Well I just bought the boat and it had the 200 on it. I have it in the shop getting tuned and gone through. I haven't run it yet on the water. I guess its just a fuel consumption issue mostly, I hear the old Johnsons are pretty thirsty, and I would like to have newer maintained motor on it. In Fact After it comes back from my mechanic I'm probably going to try and trade it for something in the 140-150 range. My soon to be Brother in law has the Force on an old Bayliner, but in reading about the Force outboards I hear horsepower ratings were not taken from the prop thus meaning a 125 may be a 100 as compared to other outboards. I just dont want to have to be running WOT at cruising speed.

[oldbluesplayer]

first, none of the 70's motors were rated at the prop, that didn't come into being 'till the 80's.

I run an 83 Johnson V-4 115, plenty of get up and go, nice 25 mph cruise, 30+ top end. and light. motor weight on a 20 makes a difference, the V-6 200 will be squatting in the stern at rest, but you sure won't have to work the motor hard to go fast.

the 125 Force ought to be fine, too.

Bill

[Texascoastalfish]

Thanks to all for responses. I want to get out on West Bay and near offshore Rigs ASAP. So I'll be using the 200 ( if it passes inspection ) Thanks for the clarification of HP rating. I still want to re power down to 150 or below.
Anyone want to trade ?

[Bushwacker]

Amen to Bill's advice! I ran the same rig for over 30 years with a 115 V-4, including 6 trips to the Bahamas. I believe the boat will generally ride better with the lighter motor. I couldn't cruise as fast as the V-6's in flat water, but it's always choppy on the Bahama Bank, and I had no trouble staying with them when it got choppy. What you have to remember is that the 20' hull is relatively narrow compared to newer boats, which is one reason it rides so well! When it was designed back in the mid-60's, the biggest motors available only weighed about 300 lbs.
As motor weight goes above that the boat becomes progressively less well balanced IMHO, especially the sf/cc which is more stern heavy than the Seafari to begin with. With my old 1975 115 I could plane at 12-14 mph which is nice capability to have when it gets rough; I suspect min planing speed is a fair amount higher with a heavier V-6. Avg mpg on the Bahamas trips was 2.8 mpg with very heavy load. It's about 4.5-5 mpg with the new motor but you can't justify cost of a new motor based on fuel usage alone, even at $4/gal! Only downside of the smaller motor is that you may not be able to outrun thunderstorms, so you need to watch the weather a little closer, but good it's good seamanship to always do that anyway!

[Fr. Frank]

in reading about the Force outboards I hear horsepower ratings were not taken from the prop thus meaning a 125 may be a 100 as compared to other outboards

This is not true. By the time AMF-Brunswick changed the Chrysler name to Force in 1984, horsepower was rated at the prop-shaft by all outboard manufacturers. Even the 1982/83 Chrysler motors were horsepower rated at the prop.

Your 125/120 hp Force is a good motor, and will push a 20' just fine. It will require a bit more time in maintenance than a new motor, though, especially in corrosion prevention.

I happen to really like those old Chrysler motors. As long as you took care of them, and really important, DIDN'T MESS WITH THE CARBURETORS, they were almost bulletproof.

The Tillotson carbs were really simple, and easy to mess up, as well as easy to repair.

I used twin Chrysler 105 hp motors on my 25 Mako CC commercial fishing boat back in 1976 in the Keys. They never failed to start, never required more than ordinary maintenance, and ran 10-12 hours a day, every day, flawlessly.