I've got my eye on a new Yamaha 4 stroke 8hp for my Macgregor 25. Would a the model with 15" shaft be okay?
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15" Possible, but not very Convient
You can use a 15", if the motor mount is lowered far enough. The problem is that the tiller and controls may be too low for convience. My guess is that you would be better off with a 20" or even longer. A 20" on my 23 puts the power head too low. A 15" works fine on my American Fiberglass D-18.
You can use a 15", if the motor mount is lowered far enough. The problem is that the tiller and controls may be too low for convience. My guess is that you would be better off with a 20" or even longer. A 20" on my 23 puts the power head too low. A 15" works fine on my American Fiberglass D-18.
N
norman
long is best
My short shaft motor on a mac 22 works as long as there are no waves, but in 1 foot waves, it begins to pick up air with the cooling water. In 2 foot waves, it gets so much air that it overheats and shuts down. That left me stranded in open water with a thunderstorm bearing down, and shoal water downwind. The anchor held, and after the motor cooled, it ran OK, but I moved the mount down 2 inches. I'm shopping around locally for a long shaft motor. Mounting low means that a following sea will douse the motor with water, and if it is running and sucks water in, you have expensive trouble. My overheating event wasn't serious because the motor was idling when it shut down. I was getting the sails secured and had started the motor to be ready!
My short shaft motor on a mac 22 works as long as there are no waves, but in 1 foot waves, it begins to pick up air with the cooling water. In 2 foot waves, it gets so much air that it overheats and shuts down. That left me stranded in open water with a thunderstorm bearing down, and shoal water downwind. The anchor held, and after the motor cooled, it ran OK, but I moved the mount down 2 inches. I'm shopping around locally for a long shaft motor. Mounting low means that a following sea will douse the motor with water, and if it is running and sucks water in, you have expensive trouble. My overheating event wasn't serious because the motor was idling when it shut down. I was getting the sails secured and had started the motor to be ready!
NO to short shaft
Even a little bobbing will keep your motor cavitating repeatedly, and Macs are light enough to hobbyhorse in anything but calm water. Almost all sailboats do better with long shafts, so ignore all the conditional comments and get the long one. You will regret it constantly if you don't. Also with a short shaft and the extra weight of a 4stroke, no one can go forward without lifting the stern enough to cavitate frequently, especially with any heeling or bobbing. Am I making myself clear here?
Even a little bobbing will keep your motor cavitating repeatedly, and Macs are light enough to hobbyhorse in anything but calm water. Almost all sailboats do better with long shafts, so ignore all the conditional comments and get the long one. You will regret it constantly if you don't. Also with a short shaft and the extra weight of a 4stroke, no one can go forward without lifting the stern enough to cavitate frequently, especially with any heeling or bobbing. Am I making myself clear here?
B
Bob
another vote for long
I have a 2005 Merc 8hp long shaft and the tiller is too low to use with the prop in the water on my Mac 25. I currently have the line and bungee connection to my rudder for close in manuverability. WM gave me a short shaft originally (even though I had ordered the long) and when I hung it on the Fulton mount it was obviously too short. Some other models have a cut-out transom mount and a short shaft might work, but not with the Mac 25.
I have a 2005 Merc 8hp long shaft and the tiller is too low to use with the prop in the water on my Mac 25. I currently have the line and bungee connection to my rudder for close in manuverability. WM gave me a short shaft originally (even though I had ordered the long) and when I hung it on the Fulton mount it was obviously too short. Some other models have a cut-out transom mount and a short shaft might work, but not with the Mac 25.
M
mrbill2
lake?
since the 25 has a up/down mount, maybe a short shaft on a lake... and if you have a dual use in mind. skiff.... otherwise go loooooooooong.
since the 25 has a up/down mount, maybe a short shaft on a lake... and if you have a dual use in mind. skiff.... otherwise go loooooooooong.
J
JonBill
Determining outboard shaft lengths
On the subject of choosing a Short, Long, or Extra Long Shaft Outboard Motor this is the proper way to determine what shaft length your boat requires. This post does not address a Mac 25 specifically but just generally how it's done on selecting a shaft length. You must measure your transom in order to determine what shaft length motor you need. Keep in mind that the cavitation plate on the outboard motor (this is the big flat horizontal fin looking thing just above the propeller) should be flush with the bottom of the boat. You can get away with an inch or two either way but for maximum performance it needs to be close if not exactly flush. Measure from the top of your transom to the bottom of your keel. If it is from 15" to 17" long you'll need to get a a "short" shaft. If it is from 20" to 22" long you'll need a "long" shaft outboard. Most outboard shafts are measured from the bottom of the engine mounting bracket to the cavitation plate on the lower unit. Generally most boats need either a short or long shaft although some boats require a 25" shaft (extra-long shaft) outboard. The measurement for a mounting braket should be the same approach, from the top of the bracket in the motoring position to the bottom of the keel on the transom. If you are most concerned with keeping the lower unit submerged in trailing or heaving seas to avoid cavitation "rather" than engine performance as would be the case in a traditional sailboat rather than a dual purpose boat then go with the long shaft like someone on this board suggested. However if you do go longer this will add drag and lessen engine performance. However if you have a problem with trailing or heaving seas you aren't going anywhere if your propeller is out of the water so its better to go with a longer shaft. In no case should you go shorter than the transom measurement for obvious reasons. But if you do go longer then keep in mind if you have an X or M your minimum draft just got deeper. As in all other decisions in boating its a compromise. If you are still unsure of what kind of shaft you need contact your boat dealer or manufacturer (ha!). What I am finding out is that predominately the Mac dealers are sail-boaters and are not terribly knowledgeable about outboards. I have read some really bad stories on this board about dealers that have set up the larger outboards for the X and M boats all wrong. It's good to do your own study. Even if you only want a kicker for another model Mac (like a 25 or 26S or whatever) there still are absolutes that apply to the outboard regardless of it's size to obtain maximum performance. Hope this helps, Kindest Regards to all, JonBill
On the subject of choosing a Short, Long, or Extra Long Shaft Outboard Motor this is the proper way to determine what shaft length your boat requires. This post does not address a Mac 25 specifically but just generally how it's done on selecting a shaft length. You must measure your transom in order to determine what shaft length motor you need. Keep in mind that the cavitation plate on the outboard motor (this is the big flat horizontal fin looking thing just above the propeller) should be flush with the bottom of the boat. You can get away with an inch or two either way but for maximum performance it needs to be close if not exactly flush. Measure from the top of your transom to the bottom of your keel. If it is from 15" to 17" long you'll need to get a a "short" shaft. If it is from 20" to 22" long you'll need a "long" shaft outboard. Most outboard shafts are measured from the bottom of the engine mounting bracket to the cavitation plate on the lower unit. Generally most boats need either a short or long shaft although some boats require a 25" shaft (extra-long shaft) outboard. The measurement for a mounting braket should be the same approach, from the top of the bracket in the motoring position to the bottom of the keel on the transom. If you are most concerned with keeping the lower unit submerged in trailing or heaving seas to avoid cavitation "rather" than engine performance as would be the case in a traditional sailboat rather than a dual purpose boat then go with the long shaft like someone on this board suggested. However if you do go longer this will add drag and lessen engine performance. However if you have a problem with trailing or heaving seas you aren't going anywhere if your propeller is out of the water so its better to go with a longer shaft. In no case should you go shorter than the transom measurement for obvious reasons. But if you do go longer then keep in mind if you have an X or M your minimum draft just got deeper. As in all other decisions in boating its a compromise. If you are still unsure of what kind of shaft you need contact your boat dealer or manufacturer (ha!). What I am finding out is that predominately the Mac dealers are sail-boaters and are not terribly knowledgeable about outboards. I have read some really bad stories on this board about dealers that have set up the larger outboards for the X and M boats all wrong. It's good to do your own study. Even if you only want a kicker for another model Mac (like a 25 or 26S or whatever) there still are absolutes that apply to the outboard regardless of it's size to obtain maximum performance. Hope this helps, Kindest Regards to all, JonBill
J
joe lea
Thanks! I'm going with the long shaft!
Thanks for the great responses! I do have dual use in mind for the outboard so leaning toward a 20" now rather than 15" or 25". I had a great deal on a new short shaft F8 Yamaha 8hp ($1,500) but I'm going to pass it up based on the feedback. My port of call is Point Harbor, NC on the Albemarle Sound where I'll do approx half my sailing, the balance being lake sailing around Chapel Hill, NC (Go Tarheels!) Thanks again, joe lea
Thanks for the great responses! I do have dual use in mind for the outboard so leaning toward a 20" now rather than 15" or 25". I had a great deal on a new short shaft F8 Yamaha 8hp ($1,500) but I'm going to pass it up based on the feedback. My port of call is Point Harbor, NC on the Albemarle Sound where I'll do approx half my sailing, the balance being lake sailing around Chapel Hill, NC (Go Tarheels!) Thanks again, joe lea
E
Ed
Ultra
I just got a Tohatsu ultra long shaft. 25". It works great and takes the waves just fine. My advice, measure and get as far below the hull as you can. As others said, it really depends on your pond.
I just got a Tohatsu ultra long shaft. 25". It works great and takes the waves just fine. My advice, measure and get as far below the hull as you can. As others said, it really depends on your pond.
M
mrbill
good choice
jonbill has the right idea. only thing he missed, is when the motor cavitates, it gets hotter, (it also does nothing for the impeller life to run dry). once the waterpump impeller burns up, or the motor gets too hot, thats it... game over, buy a new motor. rarely do over heated outboards get rebuilt. most often its a powerhead swap, and a lot of these small motors are not worth the labor to rebuild. ps: you can overheat your outboard for about 30 min before it stops running... (dont ask me how I know). maybe the new 4strokes have a warning buzzer... the old 2strokes dont as far as I know....
jonbill has the right idea. only thing he missed, is when the motor cavitates, it gets hotter, (it also does nothing for the impeller life to run dry). once the waterpump impeller burns up, or the motor gets too hot, thats it... game over, buy a new motor. rarely do over heated outboards get rebuilt. most often its a powerhead swap, and a lot of these small motors are not worth the labor to rebuild. ps: you can overheat your outboard for about 30 min before it stops running... (dont ask me how I know). maybe the new 4strokes have a warning buzzer... the old 2strokes dont as far as I know....
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