Re-powering a MacM from 70 HP up

[Octaman]

Greetings from Athens, Greece.

Our 2004 26 has given us great pleasure in the past 6 years and we are looking forward to many more good years to come. We love the Mac.

In the course of continuously maintaining and upgrading this unique boat, we feel it is time for us to replace a great 6 year old (heavily worked) engine with a new one that will hopefully serve us for another round of good years to come.
My two concerns being,
a. to enhance reliability by having a new engine again, and,
b. to acquire a little more boost in the process, that will contribute to better planing capability and whatever increase in cruising speed we can gain.

The topic of finding the right engine for the Macs has been discussed at length in many good postings.
Nevertheless, I have decided to start this new thread that specifically focuses on the and to those Mac owners that already have or have had the Suzuki DF70 (1.300 cc) 4-stroke and know the feeling of ‘want’ for just a little extra power for those calm days when the water is flat and the M hull needs a little more power to level out properly without being worked at WOT.

I welcome comments and suggestions, especially from Mac owners that have been through the process of re-powering from a 70 up (if any) and those owners that already have bigger engines on their tranoms.

To get the thread going, I would like to share my considerations with you as far as candidacy for the next engine is concerned:
- Suzuki new 4-stroke DF90 (1.500 cc)
- Tohatsu 2-stroke TLDI 90 HP (approx. 1.300 cc)
- Tohatsu 2-stroke TLDI 115 HP (approx. 1.800 cc)

Your comments please, ladies and gentlemen . . . .

Octaman

[Divecoz]

OK .....no one has replied so I will mention an issue brought to my attention about just such things...
Make sure the Motor will tilt up for sailing.....Without interference with the helm seat... My 05 50HP BF EFI Mercury juuusssssttttt makes it....
Oh My Goodness I Have scratched the motor bonnet!! I had to touch that bad boy up ... More than once!! Slow Learner!!

[Octaman]

Divecoz,

thank you for taking the time to respond.

Good point on the helm seat.

I actually raised my seat when I got the Suzuki 70 in 2004 - when I first encountered the problem - so I have covered this point. I took the hinged seat off completely, and had a grp job done to it. The horizontal plane, on which you actually sit on, was raised about 12 cm (close to 5 inches) and the 70 clears the seat when raised leaving an extra 3 to 4 cm space as it swings forward. The secondary benefits from this mod are quite interesting too: a. I sit higher when powering and have better view forward off the bow, and, b. when sitting in the cockpit, just hanging out, with my back wedged in either aft corner the higher seating contributes to a very comfortable armchair effect and doubles up as a side table to place things on (for example a beer!).

As it is today, the increased space should accommodate most big out board engines in this class. Then if it is a 2-stroke, I could get more Horses for the same or similar size. If for whatever reason my next motor hits the seat I would just re-do the mod and raise the seat a little more. I am happy doing this if necessary.

Anyone out there with a Tohatsu 115 on their M transom? Please chime in.

And BTW happy Thanksgiving to all you great Mac guys in the USA.

Octaman

[JonBill]

Probably not to many responses since this has been discussed numerous times before. I haven't visited this website but once or twice in the last couple of years, but am not surprised the issue is raised repeatedly as more people get exposure to this water craft. I think the first discussion I got into on this was at the other Mac website over 8 years ago. I'm sure if you do a search of this topic you will find a considerable amount of comments, opinons and discussions and even some that got fairly heated at the time, but a lot of good info by doing a search both here and at the other site. Some of those discussions several years ago on this subject got especially testy over on the other website. Basically I don't know of anyone that has "overpowered" their M or X and lived to regret it. But know of more than several that didn't and did live to regret it.

Recently the newer 4 strokes have people enamoured. I'll stick to the 2-stroke new technology Tohatsu TLDI 90 that weighed in at just under 300lbs in Jan. 03 when I bought mine but today weighs about 330lbs. I don't know why the weight went up with the newer year make as it is the same model and technology other than they must have beefed up something. But even adding 10% more wieght still makes it about the best weight to HP ratio you can find in that range of engine size. To me the Tohatsu is a good compromise between extra weight and extra power. Noise is noise and outboard engines are all noisy and the TLDI isn't noisey enough to get me to change to a 4 stroke and add the extra weight generally associated with 4 strokes.

Personally I wouldn't put anymore than a 90 on an M or X. The stresses on the hull square as a function of speed and would recommed keeping the powered speed in the low 20's MPH for safety sake as at some point the boat will be over stressed as you exceed speeds in the lower 20's. Just an opinion. But whatever choice you make it will be the right choice for you as I doubt that you will leave anything unconsidered.

Also the great thing about the 90 is you are guaranteed to get the advertised speed while motoring in all conditions even with all the stuff you think you need to make your trip and all the people onboard that usually accompany you on your trips.
Kind Regards,
JonBill

[Octaman]

Very interesting JonBill; thank you for your input.

The stresses in the hull are a major concern in my mind, too.
I feel that the only thing that can perhaps justify a larger engine is that those that have done it have not experienced structural failures of any kind. At least not even one case that I have heard of on this forum (yet).

As one uses and familiarizes oneself with the Mac, one comes to realise that the boat is actually a lot stronger than the original impression it gives. However, it doesn't seem that anyone has a distinct knowledge or understanding of the 'breaking point' (so to say) of the vessel in this respect. So far it has been a matter of just trial and error (with no 'error')

So people experiment with bigger engines, hoping the boat will remain in one piece (smile)

On the other hand, it is not by chance that so any Mac owners at some point feel the need for a little extra power.

Anyone out there with a Tohatsu 115 hp 2-stroke on their transom?


Octaman

[jschrade]

My suspicion is that if someone damaged their Mac running it at high speeds, they likely wouldn't be eager to note it. Other than hull blisters, I cannot recollect seeing a single serious issue on the 26 motor cruisers.

I would be curious to see what size gas tanks folks carry on these boats with large engines as they would suck some serious fuel. Especially at speed.

Jim

[Catigale]

OCtaman - someone has out a massive 140 on their and I believe reported 30 kt speeds on calm water without hull damage...so it seems like that is the 'new' upper limit...

[Octaman]

Catigale

yes, I know the X you are talking about from this forum. I have not heard of a bigger motor on any Mac. I would tend to say that 140hp is out of proportion of the dual-character of the Mac. Then again, who am i to say so.

All boats are a compromise, the Mac, even more so in many ways, but also the Mac offers so much more than an average Power OR Sail boat of this size and I, am in pursuit of finding the perfect compromise in terms of powering this unique boat, based on my way of using it.
Even if I do not use the upper scale power as often (because I also like to sail or just troll around at low speeds or the condition of the sea will not allow for high speeds), I like to know the power is there when I need it and that it will plane the boat satisfactorily and at sufficient speeds.
If you are mechanically minded as I am, which I believe you are too from your postings that I have read, you may agree that sometimes it is more the feeling of getting it right, that is rewarding, than an extra mile or two of speed.

Thus the quest for the ideal engine goes on . . . . .

Octaman

[Catigale]

If I had to repower for my current use, I would probably drop down to the smallest fuel injected 4 stroke I could buy, probably in either the Merc or Nissan line...maybe a 25 HP or so. I just dont powerboat that much.

[Highlander]

If you get caught out in 15-20ft steep swells A 25-30hp eng ain't gonna push you up & over them & thats when most boats get into trouble

J
PS I am very happy with my Merc. 75HP 4-Stroke , very seldom use all the h/p . But if you are out for a wk-end & covered say 80 miles & on the last day you start to return home & your 14 hr window suddenly is reduced to say 6hrs because of impending weather its nice to have the option to say well lets drop the sails & cruise home @ 18-20mp/h. otherwise your left with either slipping the boat for a week at a close by marina if your lucky enough to get a slip & at a cost of 45$ and up a day get the bus home if their is one ! , or call a friend to come pick you up & then haul your trl back to get your boat !! . Na I like my option much better & the bigger eng's are more fuel effcient at cruising speed 18-20mp/h running at half WOT than a 50HP or less running @ WOT 12mp/h

[Octaman]

Catigale
I power a lot (more than I would really want to) but speed/time is important for me. e.g. On a weekend I may decide to take off to the nearby island of Aegina on Friday evening. If there is a favourable wind it will take me 3+ hours to get there under sail. If I motor fast (ballast empty) I can cover the distance in just over an hour. So, if I set off at 7pm, I will be in Aegina island just after 8pm well before dark in summer. If I sail, or if I motor-sail at displacement speeds I will not be in Aegina before 10pm, could be much later - this is too late for the 'Admiral' and our little girl (smile). If I didn't have a Mac, I would be setting off next day in the morning.
Equally, on Sunday afternoon when other boats set off to get back, I can stay on for another two hours at my favourite swimming spot and get back same time as the others do.
The Mac allows me to make the best of my valuable weekend. And this is the reason it was acquired in the first place.
So, if by repowering suitably I can get one or two knots more speed (preferably combined with equal or better fuel efficiency), it counts for me.

In any case, and in your case, Catigale, I would not go less than 50hp as it defeats the purpose of having a Mac in my opinion. You may be better off with a boat that has better sailing characteristics.

-------

Highlander
Good to hear you are happy with your Merc 75.
Even though we have only 5hp difference you do have 434 cc more than my DF70 (1.732 vs 1.298cc) and THAT, I believe, is what gives you the substantial advantage. I agree with all the points you raise. Thank you for your contribution to this forum.
I have been reading your postings and watching your videos. Good stuff!
You may want to have a look at my three steering mods. You may find them interesting.

Octaman

[Rick Westlake]

If I had to repower for my current use, I would probably drop down to the smallest fuel injected 4 stroke I could buy, probably in either the Merc or Nissan line...maybe a 25 HP or so. I just dont powerboat that much.

Octaman, Highlander - though I'm reluctant to disagree with an Ultimate Mac Jedi like Highlander - I'm more in Cat's camp. (And I'm maybe just a little surprised that "Catigull" didn't name a smaller, classic British product for his new powerplant. But I digress.)

I bought Bossa Nova for its economical purchase price, simple (therefore cheap-to-keep) systems, spacious cabin and trailerability - not the speed I'd get out of the Honda 50 already perched on its transom. That wasn't really even a bonus - more of a potential liability, in my eyes; a big engine that had been sitting unused for a long time; Alex started and ran it at the dock to prove it was OK, but still I didn't quite know....

I think I have run her at WOT maybe a dozen times in the past two years. Only twice because I was in a hurry to get somewhere. A couple of times to "rock the world" of some insolent J-Boater who blew by me under sail. Otherwise, mainly to "clear its throat" and give it a few minutes of full-load running. Most of the time I run the engine between 1500 and 2000 RPM, pushing at 5 kts, just to get out where the wind takes over; I could do that with less than 10 hp. It's not about the powerboating for me; it's about getting as good as I can with a vessel that's snubbed by purist sailors, getting comfortable with staying aboard a boat for longer periods of time, and getting to sail in places that are far away under sail but a day or two's travel on the highways ... learning if I could make myself "at home" on a cruising sailboat, maybe, some day.

My nephew Charlie bought a 26M with a 25-hp Suzuki last March, and he's been hinting around "if you'd even be interested in swapping engines...."

[JonBill]

If I had to repower for my current use, I would probably drop down to the smallest fuel injected 4 stroke I could buy, probably in either the Merc or Nissan line...maybe a 25 HP or so. I just dont powerboat that much.

I think a better description of that would be De-Powering not Re- Powering.

[Rick Westlake]

If I had to repower for my current use, I would probably drop down to the smallest fuel injected 4 stroke I could buy, probably in either the Merc or Nissan line...maybe a 25 HP or so. I just dont powerboat that much.

I think a better description of that would be De-Powering not Re- Powering.

Or, maybe in tune with the nuanced language that refers to "down-sizing" as "right-sizing" ... "Right-Powering."

Speaking of Catigull, I finally did get a motor for my dinghy - not a British Seagull, but a 50-year-old Evinrude Lightwin ($110 plus some repairs) ...

Then today, at Bacon Sails, I found an utterly suitable Seagull Forty-Plus for $175. Clean and good compression.

[jschrade]

Macgregor is planning a new model, the 26P with a 125HP engine on the back, purple vein graphics running down it's sides, a free set of aviator glasses and color matched Speedo suit. Sounds like a real treat.

The demo boat, Penetrator, is being tested by one of the Northwest dealers right now. It will also be offered in Red.


Jim