I don't think I need a 9.9hp for a Mac25

[patrickfarley]

I have been sailing my current boat for 3 years now. I have a 9.9hp 2 stroke engine. According to the GPS I can make 7.7 Knots into the wind at full throttle. I use lots and lots of fuel at this speed. I have never had the need to use all of the power. I have learned that my 52lb thrust electric will move the boat against a 20mph wind against the tide in a channel. I just need to drag the boat backward so the tall bow does not catch the wind and turn me around. I keep the electric for emergencies like having the return spring brake on the main engine when coming into the channel against the tide at the end of a very hot day(You can see the electric in the picture after it was used to get to the loading dock. The main engine lost the return spring and I was leaving that day. It got me to the dock the day before and then to the loading dock.).

The outboard will never die. It is older than I am(Johnson 10hp 1961) and still starts cold with 2 pulls and 1 pull the rest of the day. I think that it will last forever as long as it is taken care of properly.
I am planning to replace it with a 4 stroke very long shaft outboard. I would like to use less fuel, not have the engine come out of the water in waves and not be so loud.

I am thinking of getting a 6hp 4 stroke. It weighs about 60lbs. The 9.8 weighs 84lbs. Since I trailer the boat and take the engine off every time I move this makes a difference.

My main hesitation is that I have never tried a 6hp on my boat. Has anyone used a 6hp or less on a Mac 25 in high winds and ocean tides? Can you reach hull speed against a 20 mph wind with a 6hp? Will it hold the boat steady in front of a drawbridge with the tide and wind pushing you toward the bridge?

I try to be a fair weather sailor. However, I have gone out on days with bad weather forecasting and been caught out in 25mph wind with higher gusts. I have been caught out in surprise thunderstorms on days that were forecast for fair weather and no afternoon thunderstorms. I know that I would be ok no matter what. If needed I can through out an anchor or two or three and wait out the weather. However, as I mentioned I like to be a fair weather sailor and prefer waiting out bad weather with cable TV in a nice condo.

Will a 6hp 25" shaft get me back to the marina if the weather turns bad on a good day?

 

[justsomeguy]

Will a 6hp 25" shaft get me back to the marina if the weather turns bad on a good day?

Yep, barring extraordinary circumstances.

 

[centerline]

I think a 6hp would push the boat fine in normal conditions, but im not sure it would, effectively, in a 20kt headwind against a 3kt tide.... are there any waves?

im sure you already know this, but let me explain to make my point....

the tide and wind will either work for you or against you, depending on its direction relative to your direction.... you can push the boat to hull speed, measured only by the speed of water past your hull.... which means, if you are motoring at 5kts in the same direction as a 4kt current, you will be making 11kts headway....

if you are motoring at the same speed against a 4kt current, you will only be making 1kt headway...

you cant do anything about the hull speed of the boat, other than have a motor big enough to reach it... how much excess power you have left over in the motor after reaching a speed at which you gain an acceptable amount of headway against the current, will be what you will have to fight against the wind...

when you are rigged for motoring (sails down and stowed), knot for knot, wind vs. water, there will be less drag on that boat by the wind than there will be by the water, but as sail/hull area increases, the pressure from the wind will increase.
depending on which direction its coming from, in relation to the direction you want to go, will determine if its resistance or assistance....

you are asking about the resistance factor.... and as you already have a dependable 9.9, and you are considering a 6, means you are fine with less power, power equals speed against the wind and waves, hull speed not so much, in a displacement hull....

I know this, for what it will cost to switch motors, you can buy a lot of gas with that money.

and i know that running a motor at half throttle can, and will almost always, cause a 70% in fuel savings.... and on your boat, that means about 1.5kt speed loss. when you figure up the long term/range effects of it, I think this is a fully acceptable number that should be embraced.

so if you keep the motor you have and cut the need for running at hull speed all the time, (as you wont see as much gain as you think with the 6hp at WOT), you will then have the fuel economy you are looking for, AND have all the power you need in whatever conditions you think you will run across...

 

[Sumner]

I take it you are looking at Tohatsu, Nissan, Merc (all the same) in either the 9.8 HP or the 6 HP Sail Pro since those are the only two outboards in those lines that come in extra-long-shaft.

Not sure what I would do in your shoes. If it wasn't for the taking on and off I'd for sure get the 9.8 HP. It isn't so much about the HP as the prop and the prop on the larger engines is just much larger than on the 6.

Saying that the 6 might be just fine unless you are in an extreme situation. 3 times for a minute or so in Florida in high current situations I was real happy to have the larger prop. Hopefully being smarter now about just how severe a tidal current can get in some situations I won't be where the big prop needs to save me. You might already have that experience.

We have a 5 HP Nissan, same as the 6 HP and with a prop change it easily handled 25+ mph wind conditions on a lake but never used it with currents which have a lot higher effect on the boat than wind. Still it didn't have the even higher thrust prop of the Sail Pro on it.

We leave the 9.8 on the boat all the time except at home when I have a friend help remove it. It is just a little too much weight for me now. If I had to put it on and off I'd have to go with the 6.

Fuel mileage wise I wonder if there is much difference. We get about 10 mpg with the 9.8 but never run at hull speed even though it could. We run about 5 knots and just don't have the need to move faster. The 5 HP would also easily push the boat at 5 knots at part throttle.

So I guess no clear cut answer. If you are younger and stronger than I am at this point in life I'd maybe opt for the 9.8 HP. The real deciding factor for us was we need electric start. Ruth cannot pull start an outboard and we will not get in the situation again where if I can't that we just sit until I can like we did on Lake Powell once. Even if I'm capable, I want to know she can start the outboard and come back for me if I go overboard

Sum

[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

 

[Piotr]

We bought the 6hp 4-stroke from West Marine when the old 6hp 2-stroke that came with the boat died (in dead calm - first and only time I needed a tow. Luckily, we were 20 minutes from the marina). Sail it up and down Chesapeake each spring (down) and fall (up). With the original prop, I have no problem in the clear, or even with the waves. However, without current we get about 5 kts. The problem with the waves is the prop coming out of the water in anything higher than 1.5 feet. Running WITH the 0.5-1.2 kt current we hit 6-7kts over land. I did not notice any difference in terms of wind.
What I'm saying is that unless you plan driving far against the wind (i.e. waves) and 3-4 kts current, 6 hp is perfect. The fuel consumption is about 1/2 gal/hr so not much difference with 9.8 hp. Considering how much heavier 9.8hps are (and about $1K more expensive), I would opt for the 6 hp.
Having said that, I did not plan on changing the prop, but I might bite the bullet and try for a new one this year.

 

[patrickfarley]

After reading the replies I am leaning toward the 6hp.
I read that the hull speed of the Mac 25 is 6.43 knots. I think I am wasting my effort with the larger engine.

I really really want an engine that does not weigh so much and does not use as much fuel as my old 2 stroke.

All of my other boats were smaller than this. I just don't want to make a mistake with this choice. I am kind of hoping someone has chosen a 6hp or less and can tell me about their experiences.

Just thinking about the weight difference just about makes up my mind. I don't think my transom could handle trailering an 84 lb. outboard for 400 miles. I really don't want to carry an 84lb motor to the back of the boat and raise it up to the motor mount. Still I will do what I have to do to have a good outboard set up for the boat.

 

[patrickfarley]

We bought the 6hp 4-stroke from West Marine when the old 6hp 2-stroke that came with the boat died (in dead calm - first and only time I needed a tow. Luckily, we were 20 minutes from the marina). Sail it up and down Chesapeake each spring (down) and fall (up). With the original prop, I have no problem in the clear, or even with the waves. However, without current we get about 5 kts. The problem with the waves is the prop coming out of the water in anything higher than 1.5 feet. Running WITH the 0.5-1.2 kt current we hit 6-7kts over land. I did not notice any difference in terms of wind.
What I'm saying is that unless you plan driving far against the wind (i.e. waves) and 3-4 kts current, 6 hp is perfect. The fuel consumption is about 1/2 gal/hr so not much difference with 9.8 hp. Considering how much heavier 9.8hps are (and about $1K more expensive), I would opt for the 6 hp.
Having said that, I did not plan on changing the prop, but I might bite the bullet and try for a new one this year.

Thank you for the information. Is 5 knots your top speed full throttle or just your regular cruising speed? I usually cruise with half to three quarters throttle to get about 5.8 to 6 knots, which is why I think I can switch to a smaller outboard. I would not switch if my current outboard had a long shaft. My new outboard will definitely have the longest shaft possible and the best prop with a spare that I can find.

The other problem with my current outboard is that it goes forward like crazy and takes forever to slow the boat in reverse. I have bumped the dock harder than I wanted to on a few occasions.

 

[justsomeguy]

snip-

The other problem with my current outboard is that it goes forward like crazy and takes forever to slow the boat in reverse. I have bumped the dock harder than I wanted to on a few occasions.

A learning experience, to be sure. Just know that your boat is, most likely, a lot tougher than you might expect.

 

[StinkBug]

I have a 7.5hp 4stroke on my 25 and wouldn't go any smaller myself. Going to a 4stroke is definitely gonna help with your fuel consumption regardless. My 7.5 uses less fuel pushing my 25 than my 4hp 2stroke does pushing my dinghy.

 

[Sumner]

...The other problem with my current outboard is that it goes forward like crazy and takes forever to slow the boat in reverse. I have bumped the dock harder than I wanted to on a few occasions.

To me it sounds like the Tohatsu 6 HP extra-long shaft Sail Pro with the high thrust prop would fit you very well. If one can get by with the long shaft you can just buy that prop and put it on.

One reason we got the extra long shaft was to mount it in the water the same distance as the long shaft. That raised the head and the controls are easier to reach now for Ruth and I. I can drop it down onto the transom fairly quickly but we never did in Florida and the prop stayed in the water. We try not to move in real adverse conditions though,

Sum

[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

 

[Piotr]

Thank you for the information. Is 5 knots your top speed full throttle or just your regular cruising speed? I usually cruise with half to three quarters throttle to get about 5.8 to 6 knots, which is why I think I can switch to a smaller outboard. I would not switch if my current outboard had a long shaft. My new outboard will definitely have the longest shaft possible and the best prop with a spare that I can find.

The other problem with my current outboard is that it goes forward like crazy and takes forever to slow the boat in reverse. I have bumped the dock harder than I wanted to on a few occasions.

usually 3/4 throttle. I do not have a knot-meter, so it's difficult to estimate a true speed.The overland speed is measured with an old car GPS (in 1 kts increments). The one thing I noticed there is not much difference in speed between 3/4 and full throttle, so I usually cruise at 3/4. But, I think you should have no problem achieving a hull speed with a 4-stroke 6 hp in calm conditions.
My wife just told me that Lake Lanier is smaller than Chesapeake Bay where we are sailing (near Rock Hall) and waves are usually smaller. She also reminded me that we often go out straight into a 20 kts wind and 2 foot waves and have no problem making headway. We definitely never felt to be in any danger because we have "only" 6hp outboard. However, it's ultimately your decision. If I were sailing On a lake (except any of the Great Lakes, of course), I would go with a 6 hp myself, because even with a lighter engine, the stern already sits deeper in water than I would like. But that's just my opinion. Whatever you decide, come back and give us your opinion.

 

[Piotr]

To me it sounds like the Tohatsu 6 HP extra-long shaft Sail Pro with the high thrust prop would fit you very well. If one can get by with the long shaft you can just buy that prop and put it on.

One reason we got the extra long shaft was to mount it in the water the same distance as the long shaft. That raised the head and the controls are easier to reach now for Ruth and I. I can drop it down onto the transom fairly quickly but we never did in Florida and the prop stayed in the water. We try not to move in real adverse conditions though,

Sum

[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

Sumner, what high thrust prop are you using? is it the same diameter as the standard prop? Where do I look for one?

 

[patrickfarley]

usually 3/4 throttle. I do not have a knot-meter, so it's difficult to estimate a true speed.The overland speed is measured with an old car GPS (in 1 kts increments). The one thing I noticed there is not much difference in speed between 3/4 and full throttle, so I usually cruise at 3/4. But, I think you should have no problem achieving a hull speed with a 4-stroke 6 hp in calm conditions.

Thanks again.
It sounds like you are getting near or to hull speed without full throttle. I think that will do for me.
Considering the weight of the 4 stroke engines I think that 6hp should do it for me.

 

[Piotr]

Thanks again.
It sounds like you are getting near or to hull speed without full throttle. I think that will do for me.
Considering the weight of the 4 stroke engines I think that 6hp should do it for me.

That would be my advice. What you could do (if you have that option) is to borrow a 6 hp and see how you like it.

 

[Sumner]

Sumner, what high thrust prop are you using? is it the same diameter as the standard prop? Where do I look for one?

http://www.tohatsuoutboardparts.com/Props-and-Hardware.html

I have the 7.9 ............393B645121 on the 5 HP and it is fine for lakes. If I was running in currents like Florida or other similar places I'd get the SailPro below it.

7.9... 6.... 3 blade ...... 393B645121

8.375.... 6.... 3 blace

(high thrust) (6hp SailPro model) 399B645121

Sum
[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

 

[Piotr]

http://www.tohatsuoutboardparts.com/Props-and-Hardware.html

I have the 7.9 ............393B645121 on the 5 HP and it is fine for lakes. If I was running in currents like Florida or other similar places I'd get the SailPro below it.

7.9... 6.... 3 blade ...... 393B645121

8.375.... 6.... 3 blace

(high thrust) (6hp SailPro model) 399B645121

Sum
[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

Do you mean this one?
8.375.... 6.... 3 blace (high thrust) (6hp SailPro model) 399B645121

 

[patrickfarley]

That would be my advice. What you could do (if you have that option) is to borrow a 6 hp and see how you like it.

I thought about that. However, if it decided to break right then...
I have seen other Mac 25s on the lake but none in my club or our associate club.
I sail on a lake most of the time. If I was lake only I would not even think about a 9.9hp.

I usually make it down to Florida 3 or 4 times a year(in-laws). They like to see the kids and they always save a few jobs for me to do while we visit.
They live in Sarasota. I have started exploring further south. Took the small sailboat to Don Pedro Island State Park last trip. I am planning to explore further this summer. Panama City area....Cayo Costa...

 

[patrickfarley]

http://www.tohatsuoutboardparts.com/Props-and-Hardware.html

I have the 7.9 ............393B645121 on the 5 HP and it is fine for lakes. If I was running in currents like Florida or other similar places I'd get the SailPro below it.

7.9... 6.... 3 blade ...... 393B645121

8.375.... 6.... 3 blace

(high thrust) (6hp SailPro model) 399B645121

Sum
[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

Thanks for letting me know what the recommended prop for the Sailpro. The link took me right to the chart.

 

[patrickfarley]

Now all I need is about 200 hours overtime to finance my summer trips.

 

[MrBill_FLL]

I've seen 3+ knts in some of the rivers and canals on the west coast of Fl.
prop size is the key.
Usually you have to get the larger engine and lower unit to get the larger diameter prop.