How big of an outboard

JohnnyCharms

Recruit
Joined
Jul 14, 2010
Messages
5
Good day all
Forgive the ignorance as I'm a first time boat owner and I'm not up to speed yet. I have a 1989 14ft Grumman, 25HP Johnson, armstrong starting & steering. I have the good forture of a bargan upgrade to a Johnson 50HP with electric everything & remote steer. I've looked all over the boat to try and find what the boat is rated for but I see nothing but a faded, non-legible sticker. I thought there was supposed to be a plate attached to all boats with all info about that particular craft but I guess I was wrong. The question is do I dare put this 50HP on a 14FT aluminum boat? Will the extra speed damage the seams on the hull and make it leak? The 25 moves the boat fairly well but I need more power :D. Any ideas are appreciated.
 

bigpoppakdog

Chief Petty Officer
Joined
Jul 9, 2008
Messages
437
Re: How big of an outboard

i had a 50hp on a 14ft chrysler cadet. Did she fly!!! Rating??? cant help u out with that one. Iboats does have a good reference system to check for that though.
 

robeward

Petty Officer 2nd Class
Joined
Jul 20, 2009
Messages
123
Re: How big of an outboard

I have a 15.5 fiberglass hydrasports bass boat with a 50hp Johnson and I can go 30mph just to give you something to compare to. Can't help with the rating but I would just give the company a call. I'm sure they can tell you.
 

jonesg

Admiral
Joined
Feb 22, 2008
Messages
7,198
Re: How big of an outboard

Glass boats weigh a LOT more than tinny's.
I'd say it gonna be too much.

Buy it and resell it if so inclined.
 

JohnnyCharms

Recruit
Joined
Jul 14, 2010
Messages
5
Re: How big of an outboard

Thanks for the input guys. jonesg, thats not what I wanted to hear but your probably right. I think I'd be to tempted to open it up and damage the boat. Maybe I could put a RPM limiter on it?:confused:
 

JohnnyCharms

Recruit
Joined
Jul 14, 2010
Messages
5
Re: How big of an outboard

i had a 50hp on a 14ft chrysler cadet. Did she fly!!! Rating??? cant help u out with that one. Iboats does have a good reference system to check for that though.

Was that cadet an aluminium hull? If so did you have any problems with it as far as leaks, trim problems, the physics of the whole thing?
 

Carusoswi

Seaman Apprentice
Joined
Jun 13, 2009
Messages
36
Re: How big of an outboard

Thanks for the input guys. jonesg, thats not what I wanted to hear but your probably right. I think I'd be to tempted to open it up and damage the boat. Maybe I could put a RPM limiter on it?:confused:

It's not the speed that will make your boat leak, it's a large engine pushing the boat over and into rough water that will definitely make an aluminum boat leak. You can also dent the hull up around the bow if you plow at speed into big waves.

I'm going to guess that 25 hp is the max HP for which your boat is rated. You might be able to get away with 30 HP, but more than that and I believe you risk worse than loosening up rivets and seams. Too much over the rated horsepower can make the boat dangerously unstable.

Further, the weight of the motor will rob you of passenger capacity in case you wanted to take the family out in the boat with you.

I'd grab that motor if it is in good shape at a good price, then, I'd start looking for an equally attractive deal on a slightly larger hull that is designed to handle the added weight and HP.

Good luck.

Caruso
 

Sir Robin

Petty Officer 2nd Class
Joined
Jun 29, 2010
Messages
126
Re: How big of an outboard

14 foot cherokee- 1978 35 hp Johnson- 4 blade 13'' pitch comprop No issues....... Would put 50 on it in a heartbeat;) Have seen many on creigslist set up this way, The transom is really beefy on mine... If I could find a short shaft 1969 55, I'd use it too:D
 

Rick.

Captain
Joined
Jul 30, 2006
Messages
3,740
Re: How big of an outboard

I just sold my 14 foot Grumman Traveler today. I used my Evinrude 15 HP on it, I would have put a 20hp on it but I would never have considered a 50 hp. Way too muck power for that boat. Too much weight as well I would think. You better plan an strapping yourself in as it will go so fast it could toss you out in a heart beat. Maybe a 50 on a 16 would be a more appropriate match and a heavy 16 at that. Best of luck. Rick.
 

adamsnez2

Seaman Apprentice
Joined
Apr 15, 2010
Messages
47
Re: How big of an outboard

Maybe a 50 on a 16 would be a more appropriate match and a heavy 16 at that.
heavy 16? i have a 16 alum. aroliner, would not consider it heavy in the least... rated for 50hp max. sooooooo yaaaaa..... 50hp on a 14 tinny :eek::cool:
 

Rick.

Captain
Joined
Jul 30, 2006
Messages
3,740
Re: How big of an outboard

heavy 16? i have a 16 alum. aroliner, would not consider it heavy in the least... rated for 50hp max. sooooooo yaaaaa..... 50hp on a 14 tinny :eek::cool:
Never heard of an aroliner but my 16 is on the heavy side and rated for 45HP max., but we are talking about a 14FT. Grumman here. I guess we all have opinions. Mine is that it would be grossly mis-matched. Rick.
 

ditchen

Seaman Apprentice
Joined
Mar 18, 2009
Messages
47
Re: How big of an outboard

What is the beam? Is it a welded seam or riveted? Modified V or flat hull? Any supports between floor and transom?

I had a welded seam 91 14 ft grumman with a 25hp. It was flat bottom and a 43" beam. 25hp was the max I would use.

2694135930051565062S425x425Q85.jpg


I have since upgraded the boat to a 91 sea nymph, welded seam, modified v, 72" beam. Added a remote steer and a 50hp and having no problems.

2399410630051565062S425x425Q85.jpg


When rigging, remember weight is your enemy.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: How big of an outboard

Good day all
Forgive the ignorance as I'm a first time boat owner and I'm not up to speed yet. I have a 1989 14ft Grumman, 25HP Johnson, armstrong starting & steering. I have the good forture of a bargan upgrade to a Johnson 50HP with electric everything & remote steer. I've looked all over the boat to try and find what the boat is rated for but I see nothing but a faded, non-legible sticker. I thought there was supposed to be a plate attached to all boats with all info about that particular craft but I guess I was wrong. The question is do I dare put this 50HP on a 14FT aluminum boat? Will the extra speed damage the seams on the hull and make it leak? The 25 moves the boat fairly well but I need more power :D. Any ideas are appreciated.

You are not wrong, it is supposed to have a capacity plate. And a vin number. Does it have a title? What is the model number on the title?

Go to the Grumman catalog http://www.marathonboat.com/gboat.pdf and see if you can find any 14 footers that are rated for 50hp (hint: you won't).

Use some sanity. You can get yourself killed. Weight is only part of it. Excessive speed and getting flipped out of it is important too.
 

JohnnyCharms

Recruit
Joined
Jul 14, 2010
Messages
5
Re: How big of an outboard

Its riveted therefore the 50HP is probably to much even though I really want to put it on.
 

ditchen

Seaman Apprentice
Joined
Mar 18, 2009
Messages
47
Re: How big of an outboard

The grumman I had did not have that plate either, nor the signs of it being there. Interesting enough it had all of the factory warning and info stickers.
 

Sir Robin

Petty Officer 2nd Class
Joined
Jun 29, 2010
Messages
126
Re: How big of an outboard

if it werks, this is my setup
I agree that running large motors under the influance of drugs or alcohol is unsafe.So... how much HP does Atlas Van Lines produce with its turbine. I believe that the operator is the key here. Pilot your craft not just drive it. As a captain there comes the responsibility


what gobble dee gook...... Pilot the craft wisely We ALL know what I mean;)

And I still want a 1969 55 short shaft triple for this old girl:)
 

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Sir Robin

Petty Officer 2nd Class
Joined
Jun 29, 2010
Messages
126
Re: How big of an outboard

still looking 4 a 55 triple s/s. I think it would be fun
 

Auxlarry

Petty Officer 1st Class
Joined
May 21, 2010
Messages
304
Re: How big of an outboard

Here is the general rule of thumb for capacity plates on outboard powered boats under 20'.
Check the manufacturers rating on this boat AND check what your State Boating Laws are.
Here in FL the C.G. and FWC are very keen on checking the Capacity Plates on vessels they inspect on the water. Fines are large for flagrent violations!
Be safe on the water!

LOADING & CAPACITY PLATES
The terms loading and capacity relate to the weight of
people, fuel and gear that can be safely carried. The
safe load of a boat in terms of people depends on a
number of characteristics, including hull volume and
dimension, the weight of the engine and, if an outboard,
how is it mounted. The number of seats in a boat is not
an indication of the number of people it can safely carry.
Capacity plates can generally be found on the inside
transom, or next to the helm station.
Capacity plates should never be removed, altered, or
tampered with. While it is not a Federal violation for a
boat owner to exceed the listed capacities, many states
do have statutes prohibiting the carriage of people and
gear in excess of the stated capacity, or the installation
of a motor that exceeds the recommended horse power
limit. Also, you may void your insurance policy if you are
found to have exceeded the limits stated on your
capacity plate.
The standard became effective for applicable boats
manufactured of mono-hull boats less than 20 feet in length, except sailboats, canoes, kayaks and inflatables.
The standard became effective for applicable boats manufactured after November 1, 1972. The standards
originally required the following:
Capacity Plate information by boat type:
�� Boats powered by outboards: the maximum persons capacity in pounds and maximum
weight capacity (persons, motor and gear) in pounds and maximum horsepower capacity.
�� Boats powered by inboards and stern drives: the maximum persons capacity in pounds
and maximum weight capacity (persons and gear). (The Coast Guard Safe Powering
Standard does not apply to inboards, stern drives, etc.)
�� Manually propelled boats: the maximum persons capacity in pounds and maximum
weight capacity (persons and gear).
Also keep in mind the limits defined on capacity plates apply in good to moderate weather conditions. In rough
waters, keep the weight well below the limit. People represent a "live" load; moving about affects a boat quite
differently than static loads like the engine or fuel tank. If your boat's capacity is fully used, or if the weather
becomes rough, distribute the load evenly; keep the weight low, and avoid abrupt changes in distribution. Shift
human or other weight only after stopping or slowing.
 
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