Powering an A-25 with a 2.2hp Mercury 2-cycle

[glk34]

I will admit the pic of Victoria with the 30hp outboard didn't look as bad as I thought it would. For me, I like the clean looks of the stern of the A25. A small little kicker is one thing but the larger OB would not be something I would want. Might help with slip parking though.

Iron Jack
A25

[hetek]

I did a boatdiesel.com calculation years ago when I purchased my A25 deLuxe to find the power required to push the boat to hull speed.

The magic number? 7 hp!

This obviously didn't count for windage, but it did give me the confidence to persue installing my Vetus 25 hp diesel where a Volvo 36 hp used to be. Added bonus: The Mitsubishi-based Vetus is 369 pounds lighter than the Volvo!

I also calculated that the Vetus should push the boat to within 0.8 kts of the Volvo... With 11 hp less.

[jerridsc]

How has it worked out with your 25hp repower?

[hetek]

Unfortunately the seasons changed quickly on me and I haven't been able to sea test yet. I'm actually putting the winter cover on today.

I've had the usual repower hurdles to deal with. I needed a longer prop shaft (the Vetus is short) and I had to rework the engine beds to match the Vetus mounting geometry. Those are givens with almost any repower. The instrument panel came with my engine (almost always an option) and all are now installed.

Just add weather above 60 degrees and a Summer's worth of boating ahead to make it all worthwhile. OK, I'll settle for north of 50 but it better be sunny!

Another bonus I failed to mention is that if I wanted to, I could cut the engine box down to almost nothing - the Vetus sticks up above the floor only about 5"!

[tribologist]

5”?? Make sure you dont end up with the waterline above the manifold.

Ulf

[DesertAlbin736]

Some thoughts on this subject: Having a stern mounted kicker is not a bad idea. However with a large heavy motor, especially a 4 stroke, even a 9 HP can weigh close to or over 100 lbs. That's about the amount of weight we have with the dinghy on davits & the small 2.5 HP 2 stroke which weighs 30 lbs hanging off the back. Since we stow luggage & other gear in the aft cabin we're already stern heavy. I think in terms of airplanes. If an airplane engine conks out & there's no suitable airport, road, field, golf course or other safe landing area close enough and/or or not enough altitude to reach one & do a dead stick landing you're in deep doo-doo. Less of a problem with a boat, but an ounce of prevention (ie not short changing on maintenance) is worth a pound of cure. And of course a dinghy and outboard, even a small one, can be used to tow with if you have crew aboard to steer. Last summer we fetched up some submerged but shallow sharp rocks in Tsehum Harbour on Vancouver Island on a low but luckily rising tide, and as the water started to rise I was able to tie off our dinghy to the stern quarter facing backwards & with the 2.5 HP outboard was able to back us off with no more damage to the boat than a few minor scratches & gelcoat dings on the keel. Didn't dare use main engine for fear of prop damage.

[hetek]

No worries, Ulf! It's probably more than 5" now that you mention it, but I did ponder the pros and cons of cutting it down. But, nah... it would make a lousy seat then!

Believe me, I took the Vetus formulas and calculations to heart when I did my repower. All is 100% to spec.

[nebulatech]

FWIW;
https://www.suzukioutboardteam.com/
I just ordered a 2.5hp Suzuki from this website yesterday. They told me I would get it Monday, but I checked the tracking and it's supposed to be here Friday. 2020 model, 4 stroke, built in gas tank, 29lbs. $740 was the best price I could find online (YMMV). No tax, free shipping. I had to call them to get a price. The website is pretty dated, but I'll post back whether the motor shows up and is as expected.

The 4hp goes up a bit, but the gentleman on the phone said this has about as much power as a Yamaha 3.5. We are going to use it on a dingy to pull the A25 I'm planning to buy after Christmas, so I should be able to weigh in on that experience as well.

I just shared the link because I was about to buy a used 2016 Yamaha 2.5 from FB Marketplace for $800. It might make sense to check out the new market.

[DesertAlbin736]

While actual use of the Suzuki motor is months away I'd be interested to hear how well you like that motor. In answer to questions about reliability posted on the Hobie forum a user made a good point, posting:

Just use Ethanol free [gas] or add Seafoam to what ever gas you can find. I use whatever gas with my Suzuki 2.5 and always add Seafoam and don't believe I have had any issues. Probably the same for all the outboards mentioned. Before I started adding Seafoam, I have had problems on another outboard due to the gas (stuck float and clogged idle jet).

My dinghy motor is a early 1990s vintage Tohatsu 2.5 HP 2-stroke purchased used several years ago for $250, which is very light & reliable, starts on the first pull, more than enough power to push my Gig Harbor dink as fast as I safely want to go. BUT, it is a 2-stroke with direct drive, no neutral or reverse which takes some getting used to, means mixing oil with gas, is a bit smokey, & not very fuel efficient, barely 1/2 hour running time on the 1 qt gas tank. While they're not quite environmentally correct, these old Tohatsu motors are bullet proof. One of these days I'll probably look for a 4 stroke replacement, but for now not a priority.

I used to like the idea of an air cooled Honda 2HP or the newer 2.3 HP in theory except I've read they're now built in China and not Japan anymore & heard of numerous common reliability problems including tales of woe heard directly from a friend who owned one. That said it looks like the Suzuki is a good choice. For one, it's 12 lbs lighter than the comparable newer 4 stroke Tohatsu 2.5, second, the fuel tank & gas filler cap is at the front of the motor, which makes it easier to refuel when hanging on the dinghy (duh, why didn't someone think of this before?), third it's got a twist throttle, (unlike my old Tohatsu), and fwd-neutral gear shift, and fourth it has two clamp screws (most brands do including my old Tohatsu but some don't).

Personally I don't expect to look for a new motor in the coming year. If we do our planned canal trip next summer I'll probably leave the dinghy & motor at home.

Here's a YouTube video of a Suzuke 2.5 being run in test tank. Looks sweet!

https://www.youtube.com/watch?v=hMIOXoTmaz8

Seen here is how mine is stowed on a homemade mount on the stern platform. Added bonus is having a dedicated space to stow a 2 gallon gas can, and since the motor is stowed at a level a bit lower than the stern rail it's easier to transfer to and from the dinghy. This is a 2016 photo taken before I added the Garhauer lifting davits.

[stmbtwle]

I've had a Suzuki 2.5 hp. They're a great dink motor, lightweight and easy to start.

The advantage of a 4hp over a 2.5 or 3.5 is that usually with the 4 you get an actual reverse, but for a lot more weight.

Shaft length: while a standard or long shaft may work fine in fair weather, if it gets choppy you may not be able to keep the prop in the water. Been there.

[nebulatech]

The 2.5 Suzuki showed up last Friday. I just had a chance to fire it up today (in a 5 gallon bucket). It is a good motor, but as stmbtwle points out, no reverse. The gear shifter is on the starboard side about 3 inches aft of the mounting bracket. From my initial observation, my largest concern is how I will rig a retrieval cable to the motor, as there are no holes to permanently bolt it to a transom. Yes, I've had a dingy motor slip off the back before. Poor yachtsmanship I know, but I'm in good company.

We will be using this motor on a dingy to tow my new A25 on Monday. About 2 miles to the dock. I will post back to report on conditions and performance.

The manual highly discourages oxygenated fuels (10% ethanol). I used an "ethanol-protection" additive. I never believed that ethanol was problematic when I ran bigger motors (90+ hp) but it turned out to be problematic in a 15hp 4 stroke Johnson on my last boat.

[nebulatech]

We successfully towed my new A25 with the 2.5 4 stroke Suzuki. We averaged 2 knots at near WOT. As a comparison, just two of us in the dingy allowed a max speed of 4 knots. Good little motor. We used two tanks of gas to go about 2 miles towing to the boat ramp and 2 miles back to the dock. The tide was near ebb, so minimal contribution. Conditions were like glass. No wind, no waves. I would have been interested to see how it performed in a chop, though for obvious reasons, I was thankful for the conditions at the time.

I believe my experience agrees with others' suppositions: 2.5hp is OK for towing in protected waters, but any contrary seaway would probably counter the 2 knot headway we were making. Perhaps something in the 4-6 hp range would be ideal for both dingy and limp-home propulsion.

As an aside, some other observations about the 2.5hp Suzuki; at only 29 lbs its a great little motor with the following downsides:

* The mounting hardware is a little weak. The motor slipped up several times. Only vigilance kept it attached to the dingy transom.
* There are no factory-provided holes for a permanent mounting solution (through transom).
* The gear shift ( N -> F ) is on the starboard side. The tiller handle is on the port side, making shifting a little more cumbersome than I would like.
* Not really a gripe, but when the tank runs dry, it takes about 7-10 pulls to re-prime the carbs. Best to top it off regularly.

[DesertAlbin736]

We used two tanks of gas to go about 2 miles towing to the boat ramp and 2 miles back to the dock. The tide was near ebb, so minimal contribution. Conditions were like glass. No wind, no waves. I would have been interested to see how it performed in a chop, though for obvious reasons, I was thankful for the conditions at the time.

Let's see, 2 miles (nautical or statute?) each way at 2 knots. So about 1 hour run each way. You said 2 tanks used? Was that 2 tanks each way or 2 tanks total? Specs on the Suzuki says 1 qt internal fuel tank capacity supposed to give +/- 35 minutes run time at WOT. So 2 tanks each way sounds about right?

Interesting that you found the mounting clamp to be weak. Was it a case of the clamp screws working loose or slipping even when tightened up? One thing I notice looking at online photos of the motor is that the clamp screws have simple rods so to speak as clamp screw handles, unlike the style of clamp screw handles on my Tohatsu which allow padlocking them together, preventing them from coming loose (as well as rudimentary anti-theft). The newer 4 stroke Tohatus (also re-branded & sold as Mercury & Nissan) have the same type of lockable clamp handles, but weighs in at 12 lbs heavier than the Suzuki.

Suzuki 2.5 front.jpg

tohatus 2 stroke face plate.jpg

tohatus 2 stroke.jpg

At least with the Suzuki you have fwd-neutral shift and twist throttle on the tiller handle. Almost all of these small motors have no reverse regardless of having F-N shift or not, just spin the motor around 180. While F-N shift was optional on the older 2 stroke Tohatus, my motor doesn't have that and is direct drive. Also the throttle is a little lever on the face plate. So it makes it interesting both when starting out & coming up to your destination, be it landing at the dinghy dock or returning to the mother ship. One has to push off before starting the motor, then with a pull of the starter cord it's off to the races (ready or not!). When coming up to the dock or back to the boat you cut the motor (pushing the kill switch stop button) when about 10 feet or so out from the intended target and drift the rest of the way in. A somewhat complicating factor with our Gig Harbor dink is that it has a shallow keel that prevents turning the motor all the way around the full 180 degrees for dead astern backing. And with the motor spun around for reversing you have to do a reach-around to work the throttle.

So all that said, what was your technique for towing your A25? For maneuverability I prefer lashing the dinghy to the starboard stern quarter with bow & stern lines and "pushing" rather than "pulling" with a tow line from the bow, have the Admiral steer the boat from the helm. Gives better control that way & easier to communicate with the helmsperson IMO.

DSCN4107 (1280x960).jpg

[nebulatech]

Hi DA,

I believe the actual distance is more like 2.7 statute miles. I didn't use any tracking software. I just did a rough estimate from Bing Maps. I tried using my phone's navigation app, but it is set up for cars and roads. It wouldn't measure the distance traveled, or even register our speed. I downloaded a different app to get our speed over ground(water). I just remeasured from my LCD screen in the office and a ruler using the scale (1" = 1000 feet ). It looks like 2.7 miles, give or take. We topped off the tank at the marina dock, then motored to the boat, hooked up and towed. About 2/3 of the way to the ramp, we refilled. I was at the helm of the A25, while the seller was in his dingy, so I don't have the specifics of when he topped off. I know we also topped off on the return trip, just before landing at the dock. I'm afraid my data isn't specific enough to allow calculations.

The clamps of the Suzuki are exactly as depicted in your photo. I don't know if the seller couldn't tighten them sufficiently, but they came loose several times, at least 4 times towing and once on the return trip while I was aboard. Since I didn't do any of the actual mounting or tightening, I can only speculate. His dingy transom was stainless steel, not soft wood or GRP which was likely a factor. I suppose the one solution for that case would be to slip a small wooden spacer in, like a paint stir stick and tighten with pliers. I would be afraid to use too much torque. I like the mounting handles of your OB better. The old 15hp 4 stroke Johnson I had was equipped with mounting holes beside the turn handles. I liked that much better, but that motor was VERY heavy, being a "first gen" 4 stroke.

For towing the boat, first let me disclose that the seller, although a liveaboard, wasn't the most circumspect mariner. My dad used to tease us in the Boy Scouts, "If you can't tie a knot, tie a lot." Such was the case. I didn't see a single proper knot in any of his work, not even a proper cleat knot. The A25 is missing the bow and midship cleats, along with the front windshield. The seller's approach was to make a bridle from his dingy's stern cleats using some old jib sheets I provided (non-floating line!!!), about 10 feet long, and junk-knot that to a 3/4" 3-ply line he had made fast to the helm cabin top by running the line aft through the missing windshield port, over the top and forward again. Essentially a loop around the cabin top, midships. The line drooped down to between the pulpit rails, which were already wrecked at this point from who knows what previous clamity, changing the point of effort from midships to the bow. Fortunately, we were only going 2 knots, so there wasn't enough strain to cause damage to the cabin top. The big shame is the bow cleat was in the forward accommodation, and there was sufficient hardware onboard to reattach it with a temporary backing block (short 2x4 board), but that may have been beyond the seller's grasp.

I would imagine you are beginning to understand the condition of the A25 I rescued, and perhaps enjoying some chuckles over the hi-jinks which ensued. As always, there's more to tell, but I believe I have hijacked this tread enough. I will share more details in a different thread.

[motthediesel]

This has been an interesting discussion. Just to throw in my two cents -- I have a Tohatsu 6hp that I bought about 3 years ago. My wife and I have been traveling to the US Southwest from our home in Northern NY for the last few years. We tow our old Avion trailer with our Dodge/Cummins, and we carry a Grumman Sportboat on the truck for our water explorations.

For comparison, the Tohatsu weighs 58#, has full gearshift, an onboard tank, plus a connection for a remote tank. With me alone (sitting in the center seat with a tiller extension) it will do 11 kts. With both of us aboard, and loaded for touring, it still does 8 kts. With a 6 gal remote tank it will go for HOURS. We did a trip of 40 miles on Lake Powell last year and we still had more than half a tank remaining.

Now that we have our 27FC, we managed to find a rare Grumman dinghy. (This is not ours)



Even though it's maybe a little big for it, we plan on using the same motor on this boat. I also plan to build an emergency bracket that can be clamped to the swim platform so that the Tohatsu can be mounted there in the unlikely event that "Pepe Le Peug" our prime mover, fails us. It will be fun to test, but I bet that 6hp will get us 3kts or so in flat water.

For comparison, I used to have a Chuck Paine designed Frances 26 cutter. It had no engine, but it had 12' sweeps, and a bracket for a 3hp Seagull. A 27 year-old me could do 2kts (but not for long ) with the oars, and it would do 3kts with the English kicker. Into any wind or current though, you would be struggling just to stay in place with either one.

Tom