Re: Johnson 60hp pushing a 19'
My personal opinion, is that trying to tweak an outboard motor to get a few more horsepower out of it, is a waste of time and an even bigger waste of money. First, getting the extra hp is rarely only a matter of re-jetting the carbs. There is usually more involved, such as changing the exhaust chamber, so that the cylinders will scavenge more efficiently. Even if you do get a little more power, you will either barely notice it, or you will not notice it at all.
As for whether or not you will be happy, no one else should judge that for you, unless you have a clearly stated and well thought out desire for the boat to do "X." If that were the case and that "X" happened to be that you want to be able to run at 35 mph with 4 people and fishing gear aboard, like I said previously, a 60 hp motor isn't going to provide that on a 19 foot fiberglass boat.
I have a 17.5 foot fiberglass trihull. The boat is rated for 130 hp, but I run a 1972 Johnson 65hp motor on it. That is half the rated hp, so by TD's rule of thumb, I should be unhappy. While I certainly don't want to give the impression that I am questioning his wisdom and that wisdom would, in fact, be appropriate for many people, its not the right one for me. I run a 15" pitch prop on the boat, have a top end of 29 mph (by GPS) and routinely cruise at about 22 mph, after backing off the power a bit. My typical load consists of me, two large batteries, 24 gallons of gas, several cameras, survival gear including food & water, and the usual assortment of PFDs, boothook, paddle, etc.
I am perfectly happy with my boat and I am perfectly happy with a cruise speed in the low 20 mph range. Whether that would make you happy or not, I can't say - you have to answer that for yourself.
I mentioned a 12" prop on your boat, because that's what I think you would need to be able to get the motor up to an acceptable WOT rpm. Your engine probably calls for a WOT range of 4,500 to 5,500 rpm and I doubt anything over 12" in pitch would do that, on a 19 foot fiberglass boat. For comparison purposes, my max rpm at WOT is 5,100. Remembering that my boat is probably several hundred pounds lighter and I have 5 more hp, you can see that you would have to drop below my 15" pitch value by quite a bit.
So, once again, first figure out what you want the boat to do and then do the homework to see what kind of power you will need, to get that level of performance. Whatever you do, however, don't pick a motor just because its a bargain. If it won't do what you want it to do, that bargain will be no bargain at all, in the long run.
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