Boat/Motor help ?

[Mr Bluegill]

Boat/Motor help ?

Hi all,  I currently have a Starcraft Camp Boat, 16', with a 25 HP Merc 2 stroke. The boat alone weighs 520 lbs.  I'm thinking of getting a new motor, a 4 stroke.....the same HP in a 4 stroke adds appx 60 lbs to my rig.  I think the boat's OK with that, but I tow with a small car, and it's already a struggle. So I am thinking of buying a 4 stroke 20HP....which is the same weight as my current 2 stroke 25.  Is there any way of finding out how my boat will act with a 20HP? How much slower it would be? I fish the Finger Lakes. , Any opinions or advice would be appreciated. Thanks to all.

Edited March 18, 2017 by Mr Bluegill

[ifishy]

We used to rent a 16 foot camp boat that was rigged with live well and lights it had a Honda 4 stroke 20 hp electric start that boat did 19 mph GPS speed with 2 adults in it one fat.

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[Rickbgm]

I have a 16' Grumman with a 20 hp Merc 4 stroke. It's ok but I usually fish alone or with 1 other person and I am not in a hurry. The problem with the 25 is the extra weight uses up some of the increase in power. A 30 4 stroke Merc weighs the same as a 25 and would be he a better bet.

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[steelydan]

You can change the prop, less pitch is lower top speed but quicker acceleration. More pitch is higher top speed but slower acceleration. Just be careful and stay in the recommended pitch range for the motor


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[jimski2]

HP is increased in a lot of motors by bigger carburetors or fuel injectors. Engine life is sacrificed for more speed. Do you really need more speed anyway?


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[Bozeman Bob]

60 lbs IMHO is not going to make any difference in your towing capabilities.  Seriously if it's that bad I would be looking for another tow vehicle before I would be thinking this 60 lbs is too much strain on my car. What are you towing it with ? A Smart car ? Not trying to be a smart ass but your talking less than a total of 1,000 lbs on two wheels,I could pull that. Bad advice on prop change, your prop should allow your engine to hit the recommended RPM range for maximum fuel and speed efficiency. Otherwise your putting a load on the engine with too much pitch or letting it Rev too high and inefficiently as far as fuel economy goes along with the danger of blowing it up by being under pitched. 

[steelydan]

60 lbs IMHO is not going to make any difference in your towing capabilities.  Seriously if it's that bad I would be looking for another tow vehicle before I would be thinking this 60 lbs is too much strain on my car. What are you towing it with ? A Smart car ? Not trying to be a smart ass but your talking less than a total of 1,000 lbs on two wheels,I could pull that. Bad advice on prop change, your prop should allow your engine to hit the recommended RPM range for maximum fuel and speed efficiency. Otherwise your putting a load on the engine with too much pitch or letting it Rev too high and inefficiently as far as fuel economy goes along with the danger of blowing it up by being under pitched. 

Whatever, all motors have a recommended pitch RANGE. That means you can use different pitches as long as you stay in the recommended range. I currently use 3 different pitches depending on what I'm fishing for. Been doing it for years!


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[Bozeman Bob]

They do not have a recommended pitch range, they have a recommended RPM range.. The MFG has no idea if your putting the motor on a 16' bare aluminum hull or a 19' fully loaded fiberglass hull. There is a huge difference in those two and they would not set themselves up for engine failure by suggesting a pitch without knowing all the facts.

[Bozeman Bob]

A good example would be the OPs issue. A overpitched prop is like him pulling his boat up a steep hill all the time, he is working the hell out of that engine, which in the long run will prematurely wear the engine out along with using more fuel. Under pitched is like going down that same hill only your in 3rd gear floored , way over the redline, and still using more gas than if you were in 4th gear cruising.

[steelydan]

Ok, mine does. My book gives me 3 choices of prop pitch. Which is what controls rpm. I'm not interested in getting into a flame war, just trying to give the guy a low cost option. I doubt he's going to over load a motor on a small aluminum boat


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[steelydan]

A good example would be the OPs issue. A overpitched prop is like him pulling his boat up a steep hill all the time, he is working the hell out of that engine, which in the long run will prematurely wear the engine out along with using more fuel. Under pitched is like going down that same hill only your in 3rd gear floored , way over the redline, and still using more gas than if you were in 4th gear cruising.

Yes, but that would be if he did not stay in the recommended range( rpm' or pitch)
Plain and simple, to have the same performance from the 20hp 2stroke to the same 4 stroke he will have to go down in pitch. 1 or 2. I never said to go from a 15 to a 22, or vice versus


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[steelydan]

My 90hp 2stroke had a 19 pitch, when I replaced it with a 115hp 4stroke I could barely get on plane. I had to go to a 17 pitch. I'm done hijacking his thread now. I hope the info helps


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[Xxx]

I'm with  Ifishy, we used to rent 16fter up in Canada they had 20 horse 4 strokers on them, so there was a group 24 battery in the boat to start with. Two grown men two snap-on size tackle bags, our own sonar which we used their battery, 6 gallon fuel cell, there wasn't much room left to land fish, oh ya don't forget my uncles 5 gallon coffee jug and my suitcase style lunch bag, that boat ran 17-19 in waves and 20 plus mph with that Evinrude 20 horse, now I have a 22fter with a 350 with a little extra bolt on Hp. My uncle builds motors for the race circuit and he believes it's around 300hp +or-minus a few ponies and only get 25-28 around 3200 to 3500 rpm. I personally don't think it would be that big of a deal, but if put a 50lbs of potatoes in the trunk and you need 3/4 throttle to pull out, UUH yea I'd be getting more tha VW bug.

[steelydan]

Long story short, you will like the 4 stroke more than the 2stroke. Unless you have a bass boat and feel the need to go from zero to 90 in 1/2 a second. LOL


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[Xxx]

4 minutes ago, steelydan said:

Long story short, you will like the 4 stroke more than the 2stroke. Unless you have a bass boat and feel the need to go from zero to 90 in 1/2 a second. LOL


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You bet, I'm a walleye guy, in my world it's how slow you can go, that 4 stroker did both I was impressed!! Now I have a 15hp 2 stroker for a kicker, only because that's what I had. Would I like a 4 stroker absolutely but the $$$ is rediculous in price, plus my motor keeps the mosquitos away!! LOL

[rolmops]

One alternative is an Evinrude 25hp e-tech. The weight issue is no longer much of a factor and you will have one the best engines on the market it weighs 146 pounds , the next would be a 4 stroke Tohatsu  at 157 pounds and the price is more reasonable. If you worry about the extra weight , you can always move things around in the boat, like putting the battery up front . For towing, the extra 50 pounds are really an issue because of the extra weight in the rear of your boat, you may end up having too little tongue weight.Remember that any extra weight will slow down your boat specially when it is in a strategic spot and the weight of the extra five hp may make a 20 horse more attractive speed wise. On a final note, by what I understand from your question ,you want to go fishing and not racing , so you might not care too much about the 2 or 3 mph difference if you go fishing.

Edited March 24, 2017 by rolmops
Having a hard time waking up.

[Rickbgm]

One other thing to think about is where you are going to use the boat. If it will be mostly lakes like Cayuga there are enough boat launches that you can get fairly close to where you want to fish so you don't need to run that fast. Also some smaller lakes have horse power restrictions so you need to look into that. As I said before my 20 Merc on my 16' Grumman is fine for what I do with it but I ran charters on Ontario for 10 years with my 25' and felt it was under powered with a 250hp because I made some long runs and would have liked more speed.

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[Mr Bluegill]

wow, thanks to this community for all these ideas.....I think I've boiled it down to it not being that big a deal either way. I tow w a Corolla, which has a 1500 lb capacity. so I guess the 60 extra lbs is NDB.

Conversely, it sounds like I'd not be sacrificing  all that much speed with the 20 . Still a decision to be made, but easier now.