My new 79' mako 25 motor questions

[mako19cc]

I just bought a 1979 mako 25 ft cc with a 1995 mariner 200 hung on the back. The boats rated for a max of 300hp. By today's standers its under powered. In the coming years i would like to put a new power plant on the back. I am debating between twins or a single. Right now i cant afford to go to a dealer and buy a brand new motor. I was planning on either going with a set of mercury 150's or a mercury saltwater series 250. Either option would be between the 98' and 02' range as in years. I don't have any experience with twins and would like to know the pros and cons to both options. If I go with the single 250 would losing the extra 50hp really matter? Any input would be great thanks!

 

[Frank Acampora]

Re: My new 79' mako 25 motor questions

While I don't have any experience with twin engines, if it were my boat, I would opt for the two 150s. In that size boat, the better low speed handling and power redundancy of twins would make me much more secure, especially when going offshore. Again, while a single engine is supposed to have higher top speed, in a boat that size, I don't think the extra weight and drag of twins would make enough of a difference to offset the perceived positives.

 

[mako19cc]

Re: My new 79' mako 25 motor questions

While I don't have any experience with twin engines, if it were my boat, I would opt for the two 150s. In that size boat, the better low speed handling and power redundancy of twins would make me much more secure, especially when going offshore. Again, while a single engine is supposed to have higher top speed, in a boat that size, I don't think the extra weight and drag of twins would make enough of a difference to offset the perceived positives.

That's what I was sort of leaning towards. Should make moving that big boat around the dock and in tight spaces a little easier. Also if one motor quits offshore I can limp home on one. I just want to know if there are any real downfalls to going with the twins rather the single.

 

[crb478]

Re: My new 79' mako 25 motor questions

Since you are going off shore I would also go for the twins, especially if one has a counter rotating gear case. Once you get used to it you will be able to back and maneuver it better in wind and rough seas. You also can get back on one motor, not fun, but it gets you home without a tow. You will have more drag, but with 50 more hp will probably have similar top speed. The 150's will cost more to operate with double the maintenance and the dual controls. If possible try to set them up as independent systems each with its own fuel supply and separate filters.

 

[mako19cc]

Re: My new 79' mako 25 motor questions

Since you are going off shore I would also go for the twins, especially if one has a counter rotating gear case. Once you get used to it you will be able to back and maneuver it better in wind and rough seas. You also can get back on one motor, not fun, but it gets you home without a tow. You will have more drag, but with 50 more hp will probably have similar top speed. The 150's will cost more to operate with double the maintenance and the dual controls. If possible try to set them up as independent systems each with its own fuel supply and separate filters.

As in independent fuel systems do you mean suppurate tanks? I believe it has one 100 gal and a 65 gal tank.

 

[dingbat]

Re: My new 79' mako 25 motor questions

It looks like I'm the minority.

Twins came about more so becouse of the lack of high HP motors than the need for redundancy. Reliably of early was also an issue.

A large percentage of break downs are fuel related. Twins only provide real redundancy with seperate fuel supplies.

I'm offshore 10-15 days a year. The number of single powered boat far out number twin powered on any given day. A single, inboard diesel is the norm for chartered vessels which speaks to the reliability of outboards in general more than anything.

I would take single, new yammi F350 over a pair of last generations outboards in a heart beat. Half the maintenance and half the worrying. Not to mention the increased liability with the latest generation outboards

 

[dingbat]

Re: My new 79' mako 25 motor questions

It looks like I'm the minority.

Twins came about more so becouse of the lack of high HP motors than the need for redundancy. Reliably of early was also an issue.

A large percentage of break downs are fuel related. Twins only provide real redundancy with seperate fuel supplies.

I'm offshore 10-15 days a year. The number of single powered boat far out number twin powered. A single, inboard diesel is the norm for chartered vessels which speaks to the reliving issues of outboards more than anything. I would take single, new yammi F350 over a pair of last generations outboards in a heart beat.

 

[b.gagnon]

Re: My new 79' mako 25 motor questions

I think that hp rating's on boats over 20' are just guidelines not law...That's a big boat even for twin 150's when loaded up....

 

[mako19cc]

Re: My new 79' mako 25 motor questions

The only problem I have is probably going to be the weight. If i throw twin 225's on the back i would imagine the stern will sit low in the water.

 

[greenbush future]

Re: My new 79' mako 25 motor questions

That's what I was sort of leaning towards. Should make moving that big boat around the dock and in tight spaces a little easier. Also if one motor quits offshore I can limp home on one. I just want to know if there are any real downfalls to going with the twins rather the single.

Downfalls Yes: fuel, syncing these to run well, prop(s), batteries, wiring, throttles or all new controls, fuel tanks, and fit and finish on your transom, will twins even fit? How about how it will change the ride both bad and good.

I think in the end, it will cost more to run twins, but that may not matter for you. Show us what you have, that may help us, help you.

And for the record I have a main motor, then a kicker, then a trolling bow mount so I understand the interest in redundancy. I would still take a new single screw.

 

[dingbat]

Re: My new 79' mako 25 motor questions

The only problem I have is probably going to be the weight. If i throw twin 225's on the back i would imagine the stern will sit low in the water.

Why put 450 hp on a 300 hp boat? 300 hp will push that boat 40+ mph