Auxilliary Advice for Driver 440 Sportsboat

[driver440]

I am looking to put a dropdown auxilliary engine bracket on the back of a 14 foot deep V hull sports boat so that I can mount a lightweight outboard in case of breakdown. All I am after is something reliable to get me home should my main engine ever pack up. <br />For cost reasons, I am hoping a suzuki DT2.2, Tohatsu 2.5s or Mariner 2.5 might do the trick in an emergency. Can someone confirm this would be adequate enough to move a boat this size less than say 2 miles in reasonable conditions.<br />Is there anything to choose between manufacturers and engines in this range? Any recommendations. Appreciate your guidance.<br />Thanks, Dave

 

[CATransplant]

Re: Auxilliary Advice for Driver 440 Sportsboat

Well, those would move the boat, but not well. If there's a headwind or any current, neither will probably do much at all.<br /><br />I'd be looking for a 5hp or 6hp for that boat. That way, you'll make some decent headway. I'm assuming that you're operating in salt water. If so, you need an auxilliary large enough to move you at hull speed. A 5 or 6hp will do that quite nicely on a 14 foot boat. the 2-2.5 hp will not.

 

[ratracer]

Re: Auxilliary Advice for Driver 440 Sportsboat

I'd second that. A 2.5HP would move you at a slow crawl on a calm day, but you'd be lucky to even stay put in a chop or if you were trying to travel against a headwind.<br /><br />Since you're in the UK, something like the 5 HP Tohatsu 2- or 4-stroke, or a good used 6HP JohnnyRude IMO would be good choices. You'd have to consider whether you would want an internal vs external tank.

 

[driver440]

Re: Auxilliary Advice for Driver 440 Sportsboat

Thanks for the advice guys. I may have to compromise with something between 2.2 and 5hp unfortunately but I take the point about the 2.2 not being man enough. One remaining question, and please forgive my ignorance, what did you mean by 'large enough to move you at hull speed'?

 

[CATransplant]

Re: Auxilliary Advice for Driver 440 Sportsboat

OK, a planing boat, like other boats, also has a "hull speed" which is the speed the boat will go without planing. Just mushing through the water, a boat can only go so fast without the application of extraordinary amounts of power.<br /><br />When you're hunting for an auxiliary motor, you're best off finding one that will push the boat to its natural hull speed at wide open throttle. Any more horsepower will be wasted, unless it's enough to plane the boat.<br /><br />Your boat's hull speed is probably on the order of 5-6 mph. A 5-6 hp motor will probably push a 14' v-hull boat to that speed. A 10 hp motor will probably add 1 mph to the speed, by sheer force. You'd probably have to go to 25hp or so to plane the boat.<br /><br />Having too small an auxiliary outboard means that you'll be going to slowly to make good headway, especially in current or a headwind. It can be worse than nothing, really. <br /><br />You might want to consider a late-model used outboard to bring the price of one the right size into your budget restrictions. I wouldn't bother with anything under 5hp, and 6 would be even better.