Suzuki DF60AV or DF90A ?

[JaxMacX]

We are looking to repower. I am seriously considering the DF60AV given that i would like to have better control at slower speeds ... our primary boat dock is perpendicular to the river current. The new 2023 DF60AV seems to have changed and now will accept up to a 14 inch prop. I recall reading that yours was at 9. Am I misunderstanding? What is the benefit of having a 14 inch prop? How would that impact cruising speed or top speed?

[OverEasy]

Hi JaxMacX!

Per the Suzuki Factory Engineering Rep it is highly recommended that the engine be able to get to the max continuous rpm level without having the computer over-speed limiter kick in. Having too large a prop will prohibit the engine from reaching its best operational power & efficiency capability. Too large a prop will lug the engine (low peak RPMs) which isn’t in the engine’s best interest for durability…sort of the same thing with a car in too high a gear at low RPMs.

When we went through our prop matching we first started with a larger prop … a 10 or 11 pitch I believe… but the engine couldn’t get much passed 4500 rpm of the recommended peak operational rpm…(effectively lugging the engine)… and peak travel speed was also limited.
We tried three blade and four blade props. The best peak travel speed and operational max engine rpm for Over Easy (with & without ballast) was obtained with the 9 pitch three blade prop at 5500 rpm ( max limit is 6300 rpm). Yes this is a bit lower than max but as we’re not out to break the sea level sound barrier it works for us …. That and as most of our travel has been and is anticipated to be at hull speed it what works for us which is about 2000 - 2500 rpm.

Once we get back into the estuaries around Beaufort SC we’ll try and do some data runs and log the results.
We were having too much fun playing with our new engine to stop grinning long enough to be bothered with getting into the technical data gathering.

Anyway that’s what we settled on and based upon our travels so far on Lake Winnipesaukee and Lake Champlain it works very nicely for our application. A boat heavier or lighter than Over Easy would probably need a different set up. That why it’s important to go through the process to get your particular set up of boat and engine and loading matched to the appropriate prop.

Best Regards
Over Easy

[Starscream]

Interesting performance results, OE.

24 to 25 mph is what I get unballasted with a 90HP turning a 14x11 prop at 5500 RPM (but a 2.0:1 reduction ratio on the ETEC 90). So similar results, there. Surprising.

Where the 90 seems to win is with ballast in, where we can maintain over 20mph at 4500 RPM. The max RPM for the ETEC90 is listed at 4,500 RPM to 5,500 RPM, so the prop is dialed in just perfectly.

I was SOOOO close to pulling the trigger on a new Suzuki DF90 when we hauled the boat out a couple of months ago, but I just baulked at the last second. I'm probably going to go back and order it at the Montreal boat show this February. THe Etec 90 has been great, but it's too loud to be a long-distance cruising motor, and that's where our usage is headed, it seems.

If anyone is interested in buying my Etec90, just send me a PM. Dealer offered me $7k CDN as a trade-in so I'd be happy to have a forum member take it for the dealer price. Montreal, QC. Maybe I shouldn't be hawking my motor on OE's post; I'll get it over to the classified section.

[Starscream]

The Montreal boat show is a flop, IMO. Lots of pontoons and fishing boats, but no sailboats. Not many vendors, and everything sold out. No show specials. Normally one has to walk through hundreds of displays just to get to the show...marinas, insurers, electronics, gear, apparel...but this year you just walk right in to the boats. I'm just not interested in a $175,000 pontoon boat.

I placed my order for a DF90A though. I have a buyer for the Etec90 at more than the dealer offered on trade-in, so that softens the blow. Suzuki said maybe August for delivery.

I'm looking forward to quiet cruising, but not to oil changes and winterizing and less space on the transom.

Now I have to choose a prop. A FB DF90A owner suggested a 4 blade 13.75x15 and that sounds right to me. Advice welcomed!

[Russ]

I'm looking forward to quiet cruising, but not to oil changes and winterizing and less space on the transom.

Oil changes on my DF70 are fairly simple. Winterizing, I just tilt it down.

[Starscream]

I'm looking forward to quiet cruising, but not to oil changes and winterizing and less space on the transom.

Oil changes on my DF70 are fairly simple. Winterizing, I just tilt it down.

Oh, no need to remove plugs and oil the cylinders and all that jazz? The Etec automatically fogged itself with oil during the winter shutdown procedure.

I agree, oil changes are easy once per year, but you still have to DO them. The onboard oil tank and winterization of the Etec made it the simplest motor possible to maintain.

[pitchpolehobie]

Hi JaxMacX!

Per the Suzuki Factory Engineering Rep it is highly recommended that the engine be able to get to the max continuous rpm level without having the computer over-speed limiter kick in. Having too large a prop will prohibit the engine from reaching its best operational power & efficiency capability. Too large a prop will lug the engine (low peak RPMs) which isn’t in the engine’s best interest for durability…sort of the same thing with a car in too high a gear at low RPMs.

When we went through our prop matching we first started with a larger prop … a 10 or 11 pitch I believe… but the engine couldn’t get much passed 4500 rpm of the recommended peak operational rpm…(effectively lugging the engine)… and peak travel speed was also limited.
We tried three blade and four blade props. The best peak travel speed and operational max engine rpm for Over Easy (with & without ballast) was obtained with the 9 pitch three blade prop at 5500 rpm ( max limit is 6300 rpm). Yes this is a bit lower than max but as we’re not out to break the sea level sound barrier it works for us …. That and as most of our travel has been and is anticipated to be at hull speed it what works for us which is about 2000 - 2500 rpm.

Once we get back into the estuaries around Beaufort SC we’ll try and do some data runs and log the results.
We were having too much fun playing with our new engine to stop grinning long enough to be bothered with getting into the technical data gathering.

Anyway that’s what we settled on and based upon our travels so far on Lake Winnipesaukee and Lake Champlain it works very nicely for our application. A boat heavier or lighter than Over Easy would probably need a different set up. That why it’s important to go through the process to get your particular set up of boat and engine and loading matched to the appropriate prop.

Best Regards
Over Easy

How did you try all of the different props? Do dealers have rentals or samples?

[Russ]

I'm looking forward to quiet cruising, but not to oil changes and winterizing and less space on the transom.

Oil changes on my DF70 are fairly simple. Winterizing, I just tilt it down.

Oh, no need to remove plugs and oil the cylinders and all that jazz? The Etec automatically fogged itself with oil during the winter shutdown procedure.

I agree, oil changes are easy once per year, but you still have to DO them. The onboard oil tank and winterization of the Etec made it the simplest motor possible to maintain.

That E-Tec was an amazing motor. Pull start with flat battery. Fogged itself? Of course it would.

[OverEasy]

Hi PitchPolePhobie!

The dealer had a selection of a couple props to tryout…. We tried to target between with a custom sized prop but the rev limiter in the computer kicked in before we ran out of throttle. We decided to keep that as our spare prop and went with the slightly coarser prop which limited our top rpm…. Not really a problem for us as we are happy cruising along at hull speed of about 6 knots (7 mph) and still have plenty of top speed for us if we need to dash anywhere.

Best Regards
Over Easy

[pitchpolehobie]

Hi PitchPolePhobie!

The dealer had a selection of a couple props to tryout…. We tried to target between with a custom sized prop but the rev limiter in the computer kicked in before we ran out of throttle. We decided to keep that as our spare prop and went with the slightly coarser prop which limited our top rpm…. Not really a problem for us as we are happy cruising along at hull speed of about 6 knots (7 mph) and still have plenty of top speed for us if we need to dash anywhere.

Best Regards
Over Easy

I bought my boat 2nd hand so I'm not familiar with the process. So did you tryout the props in the water and test speed and rpm or was it a dry test on land just watching rpm? Thanks Oe

[OverEasy]

Hi PitchPolePhobie!

All the tests were done in the water with and without ballast tank full, both 12 gallon fuel tanks full, most of our cruising stuff and three adults aboard in relatively calm water.

Air testing or water tank testing really doesn’t work well for getting a good prop match as every boat ends up being a kind of unique item… particularly for boats like our MacGregors.

Most reputable engine dealers have a reasonable selection of props available .

Changing a prop isn’t all that hard… pull the cotter key and spin the nut with the right size wrench and the prop should slide right off. We did it at the dealer ramp in about 5-to-10 minutes. It took longer to dynamically drain the ballast to be honest.

Best Regards
Over Easy

[pitchpolehobie]

Thanks OE. It seems like a simple fix. I have my 25HP that has been bulletproof since I purchased the boat. Given its reliability and my use case I plan to stick with it. Now having said that I bought one of those ebay special hangkai 3.5hp ebay specials for a dinghy a few years ago.... It came with a plastic prop. I am wondering if some 3d modeling and printing I could make a toroidal prop for it as something to play with.

[OverEasy]

Hi PitchPolePhobie!

Ohhh! That would be sooo cool!
Ya gotta keep us informed if/how you proceed with that!

We’ve been really interested in them since we became aware of them.
The increase in efficiency and decrease in noise are impressive!
The benefit to smaller motors is even more so.

We have an inflatable West Marine dingy that we’ve been toying with getting a small outboard for, (or a battery/trolling motor combo).
The intent is for a means to get ashore and back once we get on the ICW for an extended cruise.
Now that we have our “new to us” 15 ft runabout ‘SCRAMBLED’ the battery/trolling motor combo is looking to take the lead in the selection process as it could be dual use. Come to think of it SCRAMBLED could make an awesome tender (even if I bit bulky )

Best Regards
Over Easy

[OverEasy]

Hi PitchPolePhobie!

Here’s another article link you might find interesting about toroidal props…
https://hackaday.com/2023/02/06/spy-dro ... -quite-pc/

Best Regards
Over Easy

[Starscream]

I placed my order for a DF90A though. I have a buyer for the Etec90 at more than the dealer offered on trade-in, so that softens the blow. Suzuki said maybe August for delivery.

The Suzuki dealer just called me and said they will have my motor in March for April installation before the season begins. And, it's white! Awesome. I had them add the trolling controls that allow press-of-the-button increments of + or - 50 RPM for precise tuning that will help optimize long distance fuel economy. Even better, they had offered me a $500 discount if they could do the work in April, so there's another bonus!

Still no good idea on the prop, other than the Solas 13.75x15 4 blade that was recommended on FB.