size of outboard as 'spare' on I/O?

[OMCboater]

My boat is a 69' and although the engine runs like a top (still sorting a couple issues with the leg) it is 38 years old.....WOW!, when I think about that.....

Anyway, I have a bracket that bolts through the transom for mounting an outboard, beside the sterndrive. Any words of advice on selecting an outboard to put there? I want to have it more for a spare motor in case something catastrophic happens so what size should I be looking for? is 9.9 too small? is 40 too big? I am concerned about the stress on the transom from having too big of a motor on there - although I did just rebuild the transom with 2 layers of 3/4 ply and lots of glass. It's an old OMC drive so the motor/drive are not attached to the transom

The boat is a 17.5ft tri hull bowrider with a 120 horse I/O

Thanks for any advice.

 

[erikgreen]

Re: size of outboard as 'spare' on I/O?

Here's my answer: it depends

For my 21 foot boat I'm looking at a 40 horse or better. For a lake boat that size a 9.9 might do fine. If all you need is the ability to get back to the dock on a calm day, then an electric trolling motor might work for you.

If you're like me, and need the ability to maneuver radpidly out of harm's way (read: away from rocks/shallows) when there are 3-4 foot waves, then you'll want something bigger.

To answer the question you probably asked, a 9.9 horse will move your 17 foot boat at a few knots of speed, more than enough to make your way safely back to the dock.

Erik

PS: My next boat is going to be twin engine.. I'd actually prefer twin inboards, but they're hard to find around here.

 

[tommays]

Re: size of outboard as 'spare' on I/O?

A 6 HP would move it fine if you useing it in normal areas for a 17' tri-hull

which would be small lakes and bays




Tommays

 

[OMCboater]

Re: size of outboard as 'spare' on I/O?

Thanks for the input - I appreciate it. I will only be using it on lakes - some large ones but not like the 'Great' lakes so the hunt begins for a smallish outboard for 'just in case' scenarios.

 

[eriediver]

Re: size of outboard as 'spare' on I/O?

PS: My next boat is going to be twin engine.. I'd actually prefer twin inboards, but they're hard to find around here.

I now have twin I/Os. had to limp in one engine twice now. woulda had to been towed had i only had a single.

size of a spare motor will depend on your boating. Something small will be fine on a calm day, but if you find yourself in rough water with a dead engine you'll find you can't have too big of a spare.

 

[whywhyzed]

Re: size of outboard as 'spare' on I/O?

9.9 to 15HP - most of those kicker brackets are rated around 20 max.
If you get a 2 stroke and it's only for emergencies - you can just carry a whole bunch of 2 stroke oil for your main tank.

 

[Boatist]

Re: size of outboard as 'spare' on I/O?

I would get a 15 HP and a EZ Steer. The reason is the 15 is the same weight as the 9.9 but has more power. On a lake with calm winds and no waves a 6 Hp would be fine, but that not when you have problems. You have problems when the wind is blowing and the chop is getting bigger. Trying to steer into the wind and chop is hard with a small motor. The motor needs to be able to push the stern around faster than the wind and chop can push the bow around for you to be able to steer.

I would say at least a 8 HP with a high thrust prop. Top speed even with the 15 HP would be about 5 MPH.

EZ steer connects the I/O and the Outboard together so you can steer with the steering wheel when running on the small motor.

I have a 15 HP on my 21 foot Aluminum Runabout Modified V hull. I can troll as slow as .5 MPH. Top speed with a 4 blade hight thrust prop is 5.1 MPH. My boat weighs 2800 pounds dry.

 

[Don S]

Re: size of outboard as 'spare' on I/O?

Moving to Boat Topics and Questions (not engine topics)

 

[ondarvr]

Re: size of outboard as 'spare' on I/O?

Get a long shaft if possible, this will help keep the prop in the water when the waves get larger, it makes no difference how much HP you have if the prop is spinning in the air. Get the best motor you can afford in the 6 to 15 HP range, a 2 horse that runs is better than a 15 that doesn't.