50 hp enough?

[Cold Atlantic]

I have a 20 foot Eastporter. I currently have a 50 hp Johnson on it. For a 20 foot boat it is not terribly heavy. I have however built a center console and will have a live well and fishing gear etc on it. I was looking for a 70 to 90 hp motor but this one popped up and was in pretty good shape so I bought it. Now I am wondering if I should have gone with a slightly larger motor. I am not looking for any speed but would like to have enough power to get the boat up to 20mph or so.

So what do the pros have to say?

AL

 

[Scott Danforth]

how much did your boat weigh prior to adding a bunch of stuff
how much does it weigh now
what is the boat rated for in both hp and weight

 

[Cold Atlantic]

I have no idea about its weight right now. I have added about 150 in console, battery, radio etc. The info plate has been removed by previous owner. One formula I used to figure out the weight rating said 1250 pounds of cargo. I have no way to weigh it right now.

 

[dingbat]

The boat is rated for 100 hp.
I live by the 75% rule....75 hp min.

IMHO 50 hp would be rather doggish but it not my boat

 

[Cold Atlantic]

Ding, That is what I was thinking. I will have to try it out and see if I can live with it. I was looking at a brand new Evinrude 60 HO but too much money for my wallet right now. It was tempting with a 10 year warranty.

Are you familiar with this style of boat? It used to be used as a lobster boat by a young man that beat the hell out of it on the rocks. I refinished and patched it last year and will be striper fishing this year with it.

AL

 

[Sea Rider]

A boat is rated for max number of passengers and max HP. In your particular case what's the max stated number of passengers and HP transom rated for ? Do you plan boating with how many souls on board ?

Don't need going for max HP rated for if number of passengers/load will be much less than transom rated for. To get the max out of that 50 HP-OB will need to sit OB at the sweet transom height, trim it well, distribute deck weight evenly, install a tach, go for a wot spin as loaded and check achieved max wot rpm.

Compared it to factory stated wot rpm range to check if OB revs at least middle to max wot rpm range, from there can go for a prop maximization with less pitch prop or even re pitching current prop at a prop shop to pull wot revs up if in need.

If OB is in excellent running shape should have no problems achieving 20 MPH or way more, just prop OB right for the total load you'll be boating with..

Happy Boating

 

[Cold Atlantic]

Thanks.rider that makes sense. I have no manufacture tag on the boat. I found a formula online that siad it was rated forn1250# and 6 or 8 person. This is an old style work boat. You have given me the info I need. Ty much.

Al

 

[Cold Atlantic]

Also the motor height on the transom came out perfect. This motor was on an old wooden 17 foot boat that was at end of life. So the prop will be in question.

 

[Sea Rider]

Assume that OB is equipped with a prop, if so, that will be your starter prop, need to tach current prop at wot as currently loaded, depending on the wot rpm achieved and being a under powered OB will surely need to drop some pitches to bring wot rpm higher towards middle or max wot rpm range.

Post wot rpm achieved with current prop, can go from there maximizing pitches to take all those 50 horses out of that OB,

Happy Boating

 

[jimmbo]

A 50 will probably plane it, but just. You might have to put any passengers in the bow to help it get up on plane

What year is the 50? The 1971 - 74 use the same props props the V4s used, producing great low end power. In 1975 OMC started using a smaller gearcase and prop(probably to gain a 1/2 mph).

 

[Cold Atlantic]

The motor is a 1987 Johnson 50hp VRO. Compression tested to 120 and 125 psi. and runs great on Muffs. i dont know if its the original prop or not.

 

[dingbat]

All I can say is speed isn’t getting you out of the mouth of a river or inlet with the tide rolling. You need HP and throttle response

 

[Sea Rider]

OP has not specified where his boat/OB will ne used, seems for lake uses. Untill that isn't known premature conclusions about its lack of power is useless.

Happy Boating

 

[dingbat]

OP has not specified where his boat/OB will ne used, seems for lake uses. Untill that isn't known premature conclusions about its lack of power is useless.

Happy Boating

He stated the boat will be used for Striper fishing in his first post.

A handle of COLD ATLANTIC fishing Stripers (a saltwater fish) is a dead giveaway..

 

[Downwindtracker2]

For tuning my 7.5 Merc in a barrel ,I bought a laser tach at Princess Auto on sale, it was about $50. But I left the batteries in it, opps, and had to buy another at full price. It was still well under $100. Harbor Fright might have them as well.