Overpowering a Vhull

[Kmorris]

Hello all, new here and have a question about repowering my V/Utility hull. The boat is a Starcraft SL 14 of unknown age(older, but in good shape).
My question is the hull is rated to 15 hp, and I am considering purchasing a new 20 hp suzuki for it. Other than safety/insurance considerations, what should I be aware of when considering this? I'm mostly concerned about possibly damaging the transom/ hull thru excessive torque/ stress. I'm not terribly concerned about the safety issues of excessive speed as that is mostly a matter of personal prudence (can't run WOT when its sloppy on the lake). does anyone have personal experience doing this?

Thanks,
Ken

 

[Johnny]

I have only run 25hp Johnsons on my 14' Crestliner with no issues with the transom or hull.
Photos of what you have and your concerns is a huge help here in TinBoats.
I am presently installing a 35hp Johnson on my Crestliner as well as a vintage Lone Star 14' V hull.
as you said - the transom must be in good condition and of the appropriate
size for the motor...... if it is original, it may need replacing.
oh - and WELCOME ABOARD !! this is a fun place to hang out.







.

 

[Pappy]

If your transom is in good shape that is a no-brainer and easily done.

 

[bassin0331]

I had an old 14' alumacraft with a 25 Evinrude on it that would boogy. I could get 32 with just me and gear, never felt unsafe, I'm sure you'll be fine if your transom is in good shape. If not just rebuild transom

 

[Kmorris]

My only real concern is that I'm contemplating a 33% increase in HP. I'm guessing that will also mean a increase in torque/stress, but it sounds like it should be fine. Out of curiosity, what are your boats rated for?

Thanks for the replys
Ken

 

[Johnny]

my 1959 Crestliner 14' went from 30hp through 1955 to 35hp in 1957
my 1959 Lone Star 14' is rated at 35hp

 

[Crazyboat]

As a kid I had a boat rated for 7.5, I strapped a 15 on the back and went water skiing. Most boats are built to take a pounding, as long as it's in good shape the extra 5 ponies will be fine.

PS the stern never gave out, the bow did from stuffing her into waves, but the stern was fine.

 

[Pappy]

Well....as a reference, my Gheenoe is rated at 15hp (tiller) and I typically run both 25hp and 35hp on it. these engines run on a jack plate which adds stress to the transom.
My old Alumacraft, built in 1967 and the one in my avatar, is put to the task of handling a heavy 4-cylinder opposed 50hp for me on occasion. This is pretty much the limit for that hull and is a bit beyond what I normally run on it but I can put a full load in the boat and it will cruise at what a 35hp can push it at WOT. Not recommending overpowering to anyone but if your transom is in good shape structurally they will hold and run with a bunch more horsepower than we typically put on them.

 

[onthewater102]

HP rating is a function of length, width, transom height, bottom design & steering position completely independent of the structural integrity of the transom as originally manufactured.

The transom could literally be made of tissue paper by the OEM and it would still carry the same rating.

Only other concern I can think of is you do run the slight risk of running into trouble with law enforcement as it's against the law in a lot of states to overpower.

 

[Crazyboat]

Well....as a reference, my Gheenoe is rated at 15hp (tiller) and I typically run both 25hp and 35hp on it. these engines run on a jack plate which adds stress to the transom.
My old Alumacraft, built in 1967 and the one in my avatar, is put to the task of handling a heavy 4-cylinder opposed 50hp for me on occasion. This is pretty much the limit for that hull and is a bit beyond what I normally run on it but I can put a full load in the boat and it will cruise at what a 35hp can push it at WOT. Not recommending overpowering to anyone but if your transom is in good shape structurally they will hold and run with a bunch more horsepower than we typically put on them.

So please, tell me, what are your number at WOT with both the 25 and 35 HP on that Gheenoe, thing must absolutely fly.

 

[Kier]

I have a 14x48 starcraft V hull. I am not sure of the age of mine as well. It has been re-vin'd at some point. I have a 20HP Blue Band mercury on it and it does fine. Mine has a 2x6 or 2x8 across the top of the transom. The 20HP gets up on plane with 2 well and takes a bit with 3.

 

[Pappy]

The Gheenoe will run around 37 with the 3cyl 25hp on it with one person, a fuel tank, and a group 27 battery up in the bow. Prop is a production stainless 15" and has been modified.
The 35hp 3 cylinder will run about the same speed with two persons, a full cooler, fishing gear, etc. in addition to the above. Haven't run it with just me in it and no load. Sorry to hijack the thread......

 

[Kmorris]

Well....as a reference, my Gheenoe is rated at 15hp (tiller) and I typically run both 25hp and 35hp on it. these engines run on a jack plate which adds stress to the transom.
My old Alumacraft, built in 1967 and the one in my avatar, is put to the task of handling a heavy 4-cylinder opposed 50hp for me on occasion. This is pretty much the limit for that hull and is a bit beyond what I normally run on it but I can put a full load in the boat and it will cruise at what a 35hp can push it at WOT. Not recommending overpowering to anyone but if your transom is in good shape structurally they will hold and run with a bunch more horsepower than we typically put on them.

Pappy, That is exactly the sort of info I was hoping to hear. Real world experience with hanging an oversize motor.
Thanks!

 

[Crazyboat]

Well....as a reference, my Gheenoe is rated at 15hp (tiller) and I typically run both 25hp and 35hp on it. these engines run on a jack plate which adds stress to the transom.
My old Alumacraft, built in 1967 and the one in my avatar, is put to the task of handling a heavy 4-cylinder opposed 50hp for me on occasion. This is pretty much the limit for that hull and is a bit beyond what I normally run on it but I can put a full load in the boat and it will cruise at what a 35hp can push it at WOT. Not recommending overpowering to anyone but if your transom is in good shape structurally they will hold and run with a bunch more horsepower than we typically put on them.

Pappy, That is exactly the sort of info I was hoping to hear. Real world experience with hanging an oversize motor.
Thanks!

Gee I guess you didn't read the other examples given on this thread.

 

[Kmorris]

Well....as a reference, my Gheenoe is rated at 15hp (tiller) and I typically run both 25hp and 35hp on it. these engines run on a jack plate which adds stress to the transom.
My old Alumacraft, built in 1967 and the one in my avatar, is put to the task of handling a heavy 4-cylinder opposed 50hp for me on occasion. This is pretty much the limit for that hull and is a bit beyond what I normally run on it but I can put a full load in the boat and it will cruise at what a 35hp can push it at WOT. Not recommending overpowering to anyone but if your transom is in good shape structurally they will hold and run with a bunch more horsepower than we typically put on them.

Pappy, That is exactly the sort of info I was hoping to hear. Real world experience with hanging an oversize motor.
Thanks!

Gee I guess you didn't read the other examples given on this thread.

Crazyboat, my apologies; I didn't mean to slight/ denigrate/ offend.


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[davedude]

My experience is actually underpowered v-hull but I am planning an overpower of my 1973 Starcraft Mariner 14. Max hp is 40 and I am putting a 50hp on it. I am re-enforcing the transom (had to rebuild it anyway) with a new plywood/epoxy/fiberglass laminate and two additional knee braces plus stronger bracketing in the corners.
Weather has not co-operated with me, has been either too cold or too humid to do the fiberglass work so am working on the knee braces. Best of luck with your effort!