Outboard HP for my Monohull

[campbdon]

Hello, I am shopping for an outboard to power my 8000lb 29ft sailboat (Northern 29) in calm and not so calm (wind and chop) conditions. There is already an A4 onboard as original motor however I've had reliability issues over recent years and despite my education and efforts on leaning all things A4 it's giving more grief than my nerves can take. I intend to use the outboard to supplement the A4 and replace it eventually. I do need 25" shaft to reach the water and remote control so I can manouver using the boat's wheel/rudder. The choices I am considering are as follows (all prices CAD):

a) 2020 Yamaha T9.9XPB. Used. Comes with control cables. Need to purchase remote box (used $200). $3500 tax included.
The only downside on this is it's carbureted. Really prefer EFI

b) 2021 Suzuki DF9.9BTX. Comes with sidemount control box and cables. $4800 incl HST. Does have EFI

c) 2023 Tohatsu MFS9.9EEPTUL. Control box/cables extra (approx $500). TOT $5200 incl HST. Does have EFI

d) 2023 Tohatsu MFS20EEPTUL. Control box/cables extra (approx $500). TOT $5500 incl HST. Does have EFI

My ideal hp would be 15, but cannot find that with 25" and at a price I like

Both Tohatsus same weight. Extra $300 doubles my HP. Do you think the carb is significant factor considering ethanol issue with gas? Do you think 20hp will put too much stress on transom even at lower RPMs?

What would you choose if in my shoes?


Thanks in advance for any advice!
DonC

[Benz]

I would go with the Yamaha. My 8hp high-thrust 4-stroke is a hero. 31' boat, 20,000# displacement.
Ethanol issues can be mitigated by using higher octane fuel, or if you live in the happy sort of place where ethanol-free is available, use that. I have taken off and cleaned my carburator countless times, esp. in Central America where the fuel comes generously diluted with water, and it's not hard to do.
Also if you unplug the fuel line and run it dry if not going to use it for a couple days, that helps a lot.

[Adelie]

If you are motoring a lot and the fuel doesn’t get old the ethanol is less of a problem.

If the fuel is going to sit for a month or more at a time then get ethanol free or remove the ethanol.

To remove ethanol from 5g of fuel add food coloring and about 1/2gal water. Shake the fuel tank and let it sit for 15min or so. Drain off all the colored water. You should have about 1gal.

Since ethanol boosts octane about 2points start with premium fuel or add an octane booster after removing the ethanol. Be careful, some octane boosters are just ethanol.

[thomm225]

With as high as a couple of those outboard prices are it might be better just to get a nice rebuilt A4 from Moyers Marine.

They specialize in that engine.

Looks like rebuilt price is around $5500 with exchange.

https://moyermarine.com/rebuild-services/

https://moyermarine.com/video_tech-tips/

https://www.youtube.com/watch?v=DKxwfBmcTkM

[Jammer]

Any of those will work. 9.9hp will be plenty even in poor conditions.


I had a 2003 Yamaha 8. The 8 is a derated 9.9. Sold it a year ago. I did some carb work on it when I got it and it was working well until I sold it. I believe the 2020 is still mostly the same design. However in Minnesota there is non-ethanol fuel available for boats.


Depending on where you are, there may be non-ethanol fuel available.


But even if there is not, I do not believe that the problems posed by ethanol are serious enough to warrant considering one engine over another, and I do not believe that fuel-injected engines are materially more tolerant of ethanol fuel than carbureted engines. Keep fuel cool, clean, and fresh, and everything will be fine.


I have done my own work on outboards and other small engines for years and that has been my experience.

[Don C L]

So my boat is similar to yours and I have no inboard. I have a Tohatsu 9.8 with a power prop and that is plenty of power. If it were me doing this again I'd shop for a 9.9 with EFI and the "high thrust" option (which means a larger 4 blade prop and gear ratio to match,) though I have no problems with my engine at all. I just fired up the engine the other day after sitting for 4 months. I have electric start but I thought I'd just use the pull start to move the oil around a bit first before really trying to start it. To my surprise it started right up. I too run all the gas out when I shut it down.
I believe that only Honda and Yamaha offer the high thrust options though Tohatsu does advertise the option of a power prop. BTW 9.9 is sufficient, I wouldn't bother with a 15hp unless the weight and fuel economy are the same.
If you can buy or build a mount/hoist that lifts the engine straight up, so you don't have to tilt it, that is a REAL plus. The engineer who previously owned my boat built one that works really well for my boat, you can see photos of it in my albums.

I like my engine but of your list I'd choose a, but they are all pretty good. I would not get the 20 hp, that's too much. My 9.8 pushes me at nearly hull speed easily at half throttle.

[campbdon]

Thanks for the helpful suggestions. Please keep em comin!!

[Sun and Moon]

hmmm.. I thought that the problem with ethanol was that it dissolved your hoses if they weren't designed for it. Am I wrong about that?

[campbdon]

So Don CL, you slightly prefer my (a) option, so the carbed Yamaha favoured over the EFI Suzy? Both are "high thrust"

[JimsCAL]

Some random thoughts:
1. I second the option of a rebuilt A4 from Moyer. With electronic ignition and new starter and alternator, it should be very reliable.
2. If I recall at least on the older engines, the 9.9 and 15 used the same basic powerhead. Just tuned differently.
3. I would not exclude your first OB because it had a carburetor. If anything it would be simplier and easier to repair.
4. Consider the total cost - engine, mount, remote cables, etc. and compare to rebuilt A4.
5. The OB will probably have an alternator, but output will be much less than the one on the A4. Is that an issue for charging batteries when cruising?
6. Best option is to put in something like a Beta diesel. If you buy ones of those outboards with everything else needed, you are probably half way there to having a diesel inboard.

[thomm225]

Moyers rebuild comes with new 55 Amp alternator.

Outboard alternators put out around 6 Amps.

So if you don't already have solar you may need to add that cost to the cost of an outboard if you plan to cruise more than a day or two

https://moyermarine.com/rebuild-services/

https://moyermarine.com/lmexchange-2/

Prior to shipping, all MMI Exchange Engines are test run on a dynamometer at Universal’s recommended cruising power (2000 RPM) to insure that they meet original O.E.M. specifications.

[Don C L]

Originally Posted by campbdon

So Don CL, you slightly prefer my (a) option, so the carbed Yamaha favoured over the EFI Suzy? Both are "high thrust"

That's my own preference showing through, I don't have any experience with Suzukis though I have heard they are good engines. I see now that it is a high thrust engine, I missed that. I got my Tohatsu because it was used but like new and very inexpensive so I couldn't pass it up. Otherwise I would have gone for the Yamaha, even with the carb, because it's a known quantity for me. But I have no complaints about my Tohatsu so far.

Actually I think Jim has a good point about replacing the A4 with a Beta. I don't have provision for an inboard but if I did I'd be looking into the cost of getting a Beta instead of an outboard. If you can afford it, and you have the DIY skills to pull the A4 and put in the Beta yourself to make it even cheaper, I'd say that is the better option definitely.

[campbdon]

Disconnecting the 1977 A4 and craning it out through the saloon and companionway onto something that can transport it from Canada to US is just not in the cards for me. A new inboard is about worth the boat itself.The reality is, unless she is sold and the FO decides otherwise, the engine and the hull will be together "till death us do part". I think I can get the engine working in a somewhat reliable way, at least to be backed up by an OB. Was thinking of having the OB for critical manouvering in/out of my harbour and dock (with inboard in idle gear) and reserving the inboard for distance motoring until she's no longer able. So the OB is an eventual replacement and in the meantime an auxilliary and backup. I appreciate the feedback and any more opinions.

[MicHughV]

Many outboards have one dealer in a particular area...ie, don't be looking for a Suzuki in an area predominantly Yamaha, or vice versa.

In my neck of the woods, Yamaha rules, other brands of outboards are hard to come by.
So servicing for anything but a Yamaha can be a problem.
This would make choosing a Yamaha a no brainer for me.

Same can be said for other brands and locations.

[Don C L]

Originally Posted by campbdon

Disconnecting the 1977 A4 and craning it out through the saloon and companionway onto something that can transport it from Canada to US is just not in the cards for me. A new inboard is about worth the boat itself.The reality is, unless she is sold and the FO decides otherwise, the engine and the hull will be together "till death us do part". I think I can get the engine working in a somewhat reliable way, at least to be backed up by an OB. Was thinking of having the OB for critical manouvering in/out of my harbour and dock (with inboard in idle gear) and reserving the inboard for distance motoring until she's no longer able. So the OB is an eventual replacement and in the meantime an auxilliary and backup. I appreciate the feedback and any more opinions.

In that case, if it were me, and I really didn’t trust the A4 completely, I’d take it out, along with the fuel tank, and I’d take off the prop. She’ll be a little lighter, less smelly, less chance for gas fumes, a little faster, and you’ll have extra storage space (which is where I keep my batteries.) I use my engine for long distance motoring and it is fine, as long as it is submerged properly and I am not headed into a steep chop. I can get about 40 miles and still have gas left in the 6 gallon tank at a little under 6 kts. So, not diesel economy but not bad compared to my old 2 stroke 8hp. Actually my problem is I always end up with too much gas left over! I add Sta-Bil to it so it will keep. I usually carry 15 gallons since where I am I might have to motor quite a bit, usually in the morning, and then sail in the afternoons.
I am not sure if you have a lazarette that has a bulkhead to isolate the fuel tanks in the stern, but I’d definitely recommend that modification if possible.