Seafarer 228 RPM and MPH

[Mars99]

Recently purchased a 2005 Seafarer 228 with a F250 with a 3 blade prop. After a couple weeks with the boat, I feel like I’m not getting the correct mph range from the RPM levels.

Currently with 1/2 tank of gas and two people on board I’m looking at a WOT at 6000rpm and around 34 mph. On the lower range at 4400rpm I’m getting around 23mph.

Motor also seems to be sitting low. The anti-ventilation plate is completely under when the motor is trimmed about half way.

Boat has a hardtop with curtains and is bottom painted.

 

[Don Davis]

Looks like the motor is too low, I have a Suzuki DF250 and I cruise at 32mph at 4200 rpm with my Seafarer. You should be able to see the anti-cavitation plate when cruising. But it could be a prop issue as well.

 

[luckydude]

Recently purchased a 2005 Seafarer 228 with a F250 with a 3 blade prop. After a couple weeks with the boat, I feel like I’m not getting the correct mph range from the RPM levels.

Currently with 1/2 tank of gas and two people on board I’m looking at a WOT at 6000rpm and around 34 mph. On the lower range at 4400rpm I’m getting around 23mph.

Motor also seems to be sitting low. The anti-ventilation plate is completely under when the motor is trimmed about half way.

Boat has a hardtop with curtains and is bottom painted.

I have a 2020 228 with a Yamaha 250. At 6000 rpm I'd be doing around 45mph. 4400 rpm I think I'm around 30mph. If you need exact numbers, let me know and I'll get them.

You probably know that it varies a lot with conditions, it has to be pretty flat for me to get to 45mph, but your numbers seem pretty fair off.

 

[DennisG01]

A prop is a good thing to look at, but I don't think it's that. If it was, you'd be easily over-revving the engine at WOT and I'm sure you would have mentioned that.

Engine too low is easy enough to check - compare the anti-vent plate to the bottom of the hull. Should be a couple inches higher than the keel.

If the bottom paint has slime on it from sitting in the water, that could easily cause this issue.

 

[Mars99]

I have a 2020 228 with a Yamaha 250. At 6000 rpm I'd be doing around 45mph. 4400 rpm I think I'm around 30mph. If you need exact numbers, let me know and I'll get them.

You probably know that it varies a lot with conditions, it has to be pretty flat for me to get to 45mph, but your numbers seem pretty fair off.

Something seems far off. Conditions were pretty flat when I did a speed test this week, but still topping out at 6000rpm doing around 34.

 

[Mars99]

A prop is a good thing to look at, but I don't think it's that. If it was, you'd be easily over-revving the engine at WOT and I'm sure you would have mentioned that.

Engine too low is easy enough to check - compare the anti-vent plate to the bottom of the hull. Should be a couple inches higher than the keel.

If the bottom paint has slime on it from sitting in the water, that could easily cause this issue.

Will check the engine mounting, Anti-vent plate is not visible when cruising. Didnt think about slime on the bottom, will check that as well.

 

[luckydude]

Just a FYI, I had the stock 3 blade prop when I bought the boat from Grady, I think it was people here who told me to get a 4 blade from the prop gods (I don't remember where, I think it was a dude named Ken), the 4 blade did not make any noticiable difference in speed.

 

[SeanC]

2006 228 with 2006 F250 hard top, enclosure and bottom paint, half fuel, 2 people, 3 blade SWSII tops out at 43mph.

 

[glacierbaze]

Picture of your prop, preferably with numbers. A stainless Yamaha M 17 is a good prop for that set up. My 2000 with 225 OX66 is mounted in the top hole on the bracket, and next to the top hole on the motor.

 

[Ky Grady]

I just repowered my '04 228 with a F250 and I'm with the others @ 5800-6000 RPM, I'm seeing 43-45 MPH depending on conditions with 50 gal. of fuel and 2 people, no curtains on hardtop or bottom paint. Factory 3 blade 17M prop. I did have them mount my motor in 3rd hole down on motor bracket as that was where the F225 was mounted and had no issues or blow-out on hard over turns. Helps to get the motor up out of the water better.

 

[Mustang65fbk]

Sounds like you've got the incorrect prop on there or something is vastly wrong as my 2004 Grady White 228 Seafarer with a hardtop, bottom paint and a Yamaha F225 has considerably better numbers than that. After buying my boat in the fall of 2021, I emailed GW to see if I could get the performance data sheet on my boat with a Yamaha F225 on it and they emailed it to me within an hour or so. I'll attach it below but the top speed is almost 45 mph @ 6,100 rpm and the optimum cruise is 31.2 mph @ 4,300 rpm burning 10.3 gph of fuel and getting 3.03 mpg. Your boat at 4,400 rpm and getting only 23 mph as well as your top speed at only 35 mph is night and day different, especially since you've got 25 more horsepower than I do.

 

[Parthery]

Are your numbers from your GPS or from the speedo on the dash? If they are from the speedo on the dash and/or you don't have a GPS, put a speedo app on your phone that uses GPS and check your numbers.

Your RPMs are good, either you have a hub issue and the prop is slipping terribly, or you have growth on the bottom, or you have water somewhere you shouldn't which is contributing to extra weight, or your speedo is off.

How does the boat sit in the water?

 

[glacierbaze]

KYG, you have an F250, and I have an OX225, but I am curious whether your lower unit is clear of the water when tilted up in the third hole.

 

[Mustang65fbk]

Mine dips into the water when out on my mooring buoy during the summer. I'm sure there are a few different variables here like the current, how full the fuel tank is, weight of the outboard, if you have a kicker motor and so forth. But I have to imagine most with a 228 Seafarer probably have the lower unit touching the water, or very close to it.

 

[Ky Grady]

KYG, you have an F250, and I have an OX225, but I am curious whether your lower unit is clear of the water when tilted up in the third hole.

The nose of the lower unit is still just barely in the water at full tilt.

 

[Ekea]

i would get the engine at the correct height (likely higher) before you start messing with the prop. that is unless you confirm by stamped numbers that the prop is way off

 

[PNW_Drifter]

I ran aground in the dark and dinged the leading edge of my stock M17 prop. Was looking for a 4 blade spare. After trying 2 props, both way off I'm back asking if anyone has a 4blade they like or is there anything better than the 3 blade stainless M17? (it's near perfect for me). Maybe I should stop trying to beat it. I can get 5300 rpm loaded with 3-4 people and fishing gear.

4 blade Props I've tried.
- Powertech Offshore 15p L - Underpropped - took 500 extra rpm to go same speed as the M17 3blade
- Turning Point Hustler 17P L - 14.5" (under propped massively) Max speed 23 mph at 5500 rpm

Yes I talked to Ken at Prop gods, he gave the powertech recommendation.

I'm hoping to cruise at 28mph at a lower rpm than my 3 blade. Think thats possible?

 

[Ekea]

with the power tech, even if you needed more RPM, what was your fuel burn? id rather burn less fuel at higher RPM and go the same speed. also, id you talk to ken about that prop after you got your numbers?

why do you want to cruise at a low rpm? these are not large V8 motors in a car. they like to turn fast. MPG is more important than RPM for a given speed

 

[PNW_Drifter]

with the power tech, even if you needed more RPM, what was your fuel burn? id rather burn less fuel at higher RPM and go the same speed. also, id you talk to ken about that prop after you got your numbers?

why do you want to cruise at a low rpm? these are not large V8 motors in a car. they like to turn fast. MPG is more important than RPM for a given speed

The fuel burn was much worse per the yamaha guauge , I also was told by Ken and other people that 4 blade won't give you better fuel numbers. Isn't less slip what the 4 blade gives you? Prop slip is what your car doesn't have so it's not a perfect analogy. Less slip could me more efficiently I had assumed but the pitch has to be right. I haven't gotten the pitch or diameter right.

I don't have any cavitation or holeshot problems, don't do watersports but I do run heavy alot. Heavier than the test numbers in that printout above.

Who's happy with their prop on Yamaha F225?

 

[Mustang65fbk]

I have a Yamaha F225 with a stainless steel 3 bladed prop on it, though I don't know the specs offhand, but I'm pretty happy with the performance on it. The boat will do almost 45 mph with perfect or optimal conditions and also cruise in the low to mid 20's mph range while burning 7-8 gph of fuel. Can I likely do better in regards to the fuel economy numbers? Probably. Is it worth the hassle and expense of trying to get slightly better numbers? Not really. If I was going 40-50+ miles each way to the fishing grounds and wanted every bit of performance and economy then it might be a different story. That being said, most of what I do in my boat is trolling for salmon right in front of my cabin and then take the occasional cruise around the bay as well.