doug rumball
New Member
- Jun 12, 2023
- 5
- Boat Info
- prop size for 1979 225 SeaRay
- Engines
- 350 mercury 260hp
looking for any info for the original prop on a 1979 searay 225 with a 260hp /350merc thunderbolt iv
original prop size
- Thread starter doug rumball
- Start date
techmitch
Well-Known Member
- May 1, 2008
- 8,395
- Boat Info
- 1999 270 DA
- Engines
- Twin 4.3s W/Alpa I Gen II's
Welcome to CSR. Which model 225?
JHornsby3
Well-Known Member
- Nov 10, 2020
- 1,392
- Boat Info
- "Steele'y Tutz"
1992 300 Sundancer
- Engines
- Twin 4.3L W/Alpha One Gen II
I have one in the garage with a spare, complete drive. If you want it, come get it. I trip over it again and it's going to the scrap yard.
ENGINE,DRIVE AND PROP MATRIX.xls (searayweb.com)
ENGINE,DRIVE AND PROP MATRIX.xls (searayweb.com)
DaveKamp
Active Member
- Jun 9, 2021
- 189
- Boat Info
- 1970 SRV180, '77SRV220CC, 76 SRV-240FB, another SRV180
- Engines
- Mostly MerCruisers with R-MR-Alpha drives
You didn't identify the drive... but I'm guessing it was a MerCruiser R/MR/Alpha series...
If so, it would've had 1.50:1ish gear ratio and would swing a 23p stainless if you were light, or a 21p loaded... or a 21p aluminum or 19p aluminum...
If so, it would've had 1.50:1ish gear ratio and would swing a 23p stainless if you were light, or a 21p loaded... or a 21p aluminum or 19p aluminum...
doug rumball
New Member
- Jun 12, 2023
- 5
- Boat Info
- prop size for 1979 225 SeaRay
- Engines
- 350 mercury 260hp
It is a weekender
doug rumball
New Member
- Jun 12, 2023
- 5
- Boat Info
- prop size for 1979 225 SeaRay
- Engines
- 350 mercury 260hp
It’s a 23ft weekender
doug rumball
New Member
- Jun 12, 2023
- 5
- Boat Info
- prop size for 1979 225 SeaRay
- Engines
- 350 mercury 260hp
doug rumball
New Member
- Jun 12, 2023
- 5
- Boat Info
- prop size for 1979 225 SeaRay
- Engines
- 350 mercury 260hp
It’s an alpha and we’re running a 15.25x15d its a little sluggish coming out of the whole without getting onit rpm wise, its a heavy boat.
DaveKamp
Active Member
- Jun 9, 2021
- 189
- Boat Info
- 1970 SRV180, '77SRV220CC, 76 SRV-240FB, another SRV180
- Engines
- Mostly MerCruisers with R-MR-Alpha drives
So the 225 Weekender used the same basic lower hull (possibly even same mold) as the 225 Cuddy, but with the bumped-up deck, rather than the three-section cuddy's windshield. The upper structure IS heavier, but most of that weight is forward. Sometime between '77 and '79 they changed a bit of the back of the hull, eliminating a little of the rocker that appeared on the 21-24ft hulls, and they ran flatter, but because of the power-to-weight ratio, and the basic 'family' use, these hulls didn't really take advantage of climbing high to gain efficiency, and because of the size and frontal area, they had lots of wind drag.
Most of the time, guys run this category of boat at just-barely-on-plane. First time I ever recognized it, was when my Dad ran his '22 upriver, digging a huge hole in the water, basically adjusting the throttle for maximum vacuum... and it still baffles me, but my point here is, that there are situations where running a higher pitch, and putting more throttle in, will get BETTER economy, because you're up, flat, and climbed up a chine farther. FINDING that point takes some doing.
While a purist will argue that the low pitch will pull you up on plane faster (it will), and you've noted that you have to spin it up higher in RPM (you certainly will) to get it on plane, My gut feeling is that your 15 is too low to find the efficient planing attitude.
It isn't an exact match, but I've got a '79 MCM 260R drive system in my '77 SRV220CC. I'd estimate that dry weight of mine is probably no more than 500-600lbs less than your 225... and aside from the possible hull differences noted above, will have about the same planing character.
My 220CC with a 19p will run about 48mph... and that calculates to around 15% slip. Normally I'd consider that much slip to be excessive, but this is not a low-drag runabout.
Your 225, with a 15p and same general parameters is at about 38mph. My Dad's 26-ft Wellcraft 255 SunCruiser, with a 2001 Mercruiser 5.7l and Alpha One 1.5:1 and a 15p does exactly that... but I'm certain that the 255 SunCruiser, although a little lighter, has significantly more wind drag... and I'm certain that if I swapped to a 17p, would make mebbie 41, but wind drag would become a 'brick wall' after that.
I DO know, with certainty, that my 220CC gets better fuel economy at 40mph, than barely-on-plane... as while it's drawing more fuel, it is covering significantly greater distance at that higher state-of-plane.
Most of the time, guys run this category of boat at just-barely-on-plane. First time I ever recognized it, was when my Dad ran his '22 upriver, digging a huge hole in the water, basically adjusting the throttle for maximum vacuum... and it still baffles me, but my point here is, that there are situations where running a higher pitch, and putting more throttle in, will get BETTER economy, because you're up, flat, and climbed up a chine farther. FINDING that point takes some doing.
While a purist will argue that the low pitch will pull you up on plane faster (it will), and you've noted that you have to spin it up higher in RPM (you certainly will) to get it on plane, My gut feeling is that your 15 is too low to find the efficient planing attitude.
It isn't an exact match, but I've got a '79 MCM 260R drive system in my '77 SRV220CC. I'd estimate that dry weight of mine is probably no more than 500-600lbs less than your 225... and aside from the possible hull differences noted above, will have about the same planing character.
My 220CC with a 19p will run about 48mph... and that calculates to around 15% slip. Normally I'd consider that much slip to be excessive, but this is not a low-drag runabout.
Your 225, with a 15p and same general parameters is at about 38mph. My Dad's 26-ft Wellcraft 255 SunCruiser, with a 2001 Mercruiser 5.7l and Alpha One 1.5:1 and a 15p does exactly that... but I'm certain that the 255 SunCruiser, although a little lighter, has significantly more wind drag... and I'm certain that if I swapped to a 17p, would make mebbie 41, but wind drag would become a 'brick wall' after that.
I DO know, with certainty, that my 220CC gets better fuel economy at 40mph, than barely-on-plane... as while it's drawing more fuel, it is covering significantly greater distance at that higher state-of-plane.
On Sea Ray's site is a prop chart - you can look it up for your boat model and find the prop used based on the engine/drive you have.
Use the RPM - that's exactly what it's there for and the proper way to get on plane. Also make sure the drive is trimmed all the way down and use your tabs (if you have them).
Use the RPM - that's exactly what it's there for and the proper way to get on plane. Also make sure the drive is trimmed all the way down and use your tabs (if you have them).
JHornsby3
Well-Known Member
- Nov 10, 2020
- 1,392
- Boat Info
- "Steele'y Tutz"
1992 300 Sundancer
- Engines
- Twin 4.3L W/Alpha One Gen II
I posted the link above.
DaveKamp
Active Member
- Jun 9, 2021
- 189
- Boat Info
- 1970 SRV180, '77SRV220CC, 76 SRV-240FB, another SRV180
- Engines
- Mostly MerCruisers with R-MR-Alpha drives
One critical point to be aware of...
If you look at the 1979 240WE, you'll see that it has TWO listings, one with the 228, other with the 260, same 16x15C propeller spec, yet the 228 shows 4600rpm, with the 260 showing 4200rpm.
Reason this is, is because the 228 is shown with OPTIONAL gearing of 1.65:1, rather than standard gearing of 1.50:1. You'll need to know your drive's gear ratio, and GUESS (by the difference in numbers) which ratio the power package identified in the chart was using.
In MOST cases, you'll find that the upper housing has the ratio marked on the side of the drive, either on the serial tag, or stamped in the housing. Changing ratios is done by changing gears in the upper, so if the drive has been rebuild, there's a CHANCE that someone used a different ratio. If you suspect a V8 has been fitted with the 1.65:1 optional ratio, lift the top cap, rotate the gears, and look for a set of timing marks on the gears. That ratio is 24:24, each tooth meets only the same tooth on every rotation, so they must be 'timed' in order to prevent self-destruction... all other gearsets (1.32, 1.50, 1.84, 1.98, 2.40 use non-timed tooth counts. You can count teeth on these (if necessary) to determine the drive/driven tooth counts. 1.50 is 22/20, 1.65 is 24/24, 1.84 is 17/19, 1.98 is 20/24.
(you'll likely never see 1.32:1 or 2.40:1, as the former was used in 454-powered R-MR-Alpha One-Alpha One SS drives, and the latter was used in houseboats... but note that the 2.40:1 upper was (like 1.98:1) a 20/24, that's because the lower end pinion and propshaft ratio was a totally different gearset.
If you look at the 1979 240WE, you'll see that it has TWO listings, one with the 228, other with the 260, same 16x15C propeller spec, yet the 228 shows 4600rpm, with the 260 showing 4200rpm.
Reason this is, is because the 228 is shown with OPTIONAL gearing of 1.65:1, rather than standard gearing of 1.50:1. You'll need to know your drive's gear ratio, and GUESS (by the difference in numbers) which ratio the power package identified in the chart was using.
In MOST cases, you'll find that the upper housing has the ratio marked on the side of the drive, either on the serial tag, or stamped in the housing. Changing ratios is done by changing gears in the upper, so if the drive has been rebuild, there's a CHANCE that someone used a different ratio. If you suspect a V8 has been fitted with the 1.65:1 optional ratio, lift the top cap, rotate the gears, and look for a set of timing marks on the gears. That ratio is 24:24, each tooth meets only the same tooth on every rotation, so they must be 'timed' in order to prevent self-destruction... all other gearsets (1.32, 1.50, 1.84, 1.98, 2.40 use non-timed tooth counts. You can count teeth on these (if necessary) to determine the drive/driven tooth counts. 1.50 is 22/20, 1.65 is 24/24, 1.84 is 17/19, 1.98 is 20/24.
(you'll likely never see 1.32:1 or 2.40:1, as the former was used in 454-powered R-MR-Alpha One-Alpha One SS drives, and the latter was used in houseboats... but note that the 2.40:1 upper was (like 1.98:1) a 20/24, that's because the lower end pinion and propshaft ratio was a totally different gearset.
