twin outboards

[aussie_true_blue]

The boat I have has got twin 50's on the back of my mono hull which were there when I purchased it. My question is- what are the advantages of twin 50's over say a single 100hp outboard?
I am curious as to when I replace them which way to go thats is another pair of 50's or one single bigger motor?

cheers Bob:-/

[skipalong]

it could swing either way depending on coin in the pocket, twins will set you back more, BUT i have just put a pair of 115 yamahas on my 7.4 mono and getting better fuel economy than the same size boat with single 250, but again had to outlay a few more thousand. i also run upto 80nm offshore so i wanted 2 motors for safety and this also greatly enhanced stability offshore in a follow sea with two engines spread on the transom, but in this case on such a small pair of twins i guess the single would suit it down to the ground.

regards justin

[Dean1]

Twin engines will make your monohull alot more stable whilst under power especially in a following sea which is most important.

I love the feeling of having 2 motors when wide offshore for safety reasns cause you just never know what can go wrong.

Others will give you opposite opinions but thats what ive learnt and believe, I know guys that have gone to a single after twins and claim its not the same boat anymore for the worse.

Deano.

[Noelm]

OK, I have responded to this question lots of times, so here goes , twins will be slower than the same HP single, but they will push more load (but slower) they are more expensive to buy, but about the same to run, cost a bit more at service time, but not twice as much as most say, make sure you have seperate fuel tanks and lines, otherwise the perceived safety aspect just went out the window, the boat will probably never plane on one motor, so it will be a long trip home from where ever you are if you break down, and sometimes they do add some handling to a boat, but sometimes very little, idling around the crowded ramp will be a breeze, twins look good, sound great, and do give you confidence, so there you go, a quick rundown on plus and minus of twins.

[Noelm]

might as well ask, what sort of boat is it?

[aussie_true_blue]

its a hartley vixen 17ft deep vee

cheers Bob

[skipalong]

OK, I have responded to this question lots of times, so here goes , twins will be slower than the same HP single, but they will push more load (but slower) they are more expensive to buy, but about the same to run, cost a bit more at service time, but not twice as much as most say, make sure you have seperate fuel tanks and lines, otherwise the perceived safety aspect just went out the window, the boat will probably never plane on one motor, so it will be a long trip home from where ever you are if you break down, and sometimes they do add some handling to a boat, but sometimes very little, idling around the crowded ramp will be a breeze, twins look good, sound great, and do give you confidence, so there you go, a quick rundown on plus and minus of twins.

dont mean to be a pain but some of this is not true, as my boat with 2 115 yamaha 4 strokes does the same speed as a 250 yamaha 4 stroke on same size and weighted boat and reaches 38knots, true it has more torque and hole shot, same cost to run, my boat planes on one motor, provided the second is completey trimmed out of the water for less drag,

regards justin

[wrxhoon]

dont mean to be a pain but some of this is not true, as my boat with 2 115 yamaha 4 strokes does the same speed as a 250 yamaha 4 stroke on same size and weighted boat and reaches 38knots, true it has more torque and hole shot, same cost to run, my boat planes on one motor, provided the second is completey trimmed out of the water for less drag,

regards justin


If it planes with one engine it means your underpropped ( the prop pitch is too small) if propped right you shouldn't be able to plane . you can carry another prop with you ( smaller pitch) and change it then you will plane .

Don't forget you are spinning 2 props so you have more drag, its like comparing say a 5 blade prop to a 2 blade, the 5 will have the holeshot and the 2 will have the speed as long as they are fitted to the same boat/motor and they are the same pitch.
Everything been equal ( load , correct props etc..) the single set up even with the same power should be a little quicker top speed and a little slower out of the hole.
Twin set up has many advantages and one disadvantage COST.

[Noelm]

skipalong, if that is the case, then there is something wrong with the setup of the single.

[Catweb]

The safety aspect of having 2 engines is a "nice to have". Having owned 3 twin outboard set ups over the years and having done a combination of around 3000 hours over several years, I never once had to limp home on one engine. I've had twin Yams, Mariners and Johnsons. But was always comforting to know I could have if I had too.

[ozbee]

there is a third option and that is a kicker like a 20 hp or so one that is manual start as well as electric . this gives you the ability to get going after a major electrical fault or wiring battery flooding plus a motor to run around on a tinny as well. is it superior no , twins lift better,weigh more but drag more,use at least about 10 % more fuel or about fifty more horsepower to push in larger hulls and service costs. they do steer better at idle though the newer sharp skeg that are on suzuki eg do make steering a lot easier. really a matter of choice

[kokomo]

dual motors is a false economy..

the boat is heavier... needing to run dual systems to everything...

double the drag in the water...

slower top speed and higher fuel costs..

id take a single any day

[hakuna]

I have had both, twins are heavier and cost more but I found are more fuel efficient than a single, where they come into their own is if you troll or drift fish where you go to the fishing grounds on 2 motors, use one there all day alternating the motors, and 2 home. The fuel saving is not even comparitable with a single.

cheers

[ffejsmada]

Ahhhhhh, but the sound of twin motors singing is a beautiful sound.

I don't know how many times I nearly creamed my pants when my twins were singing in unison, calm day, flat out, what a sweet sound .

[dfox]

Unless there are extreme circumstances, or the boat is being used in a remote area, in this case id repower with a single 90,100 or 115hp engine. Duels on a small rig used for a bit of recreational fishing is really a waste. Keep the boat simple, modern engines (should) be reliable and have a good marine radio as back up...

[cormorant]

I think that people put too much trust in technology. If you can't paddle home you should have an alternative viable motor to hold you into a headsea or wind at least or even better get you home. The idea is to be independent not to expect people to come get you. It is no accident if you are out wide and need rescueing with a motor failure on a single motor. Do you travel in pairs or groups that make consistant satelite phone or radio contact inncase of a breakdown so you can assist and tow Better technology doesn't help prop strikes and mechanical failures.

Nah better to phone the volunteers

Makes you wonder why the police in the Torres straight incident referred to a EPIRB as petrol is required.

Twins on a V hull may be able to be mounted higher and off the centerline. There is less drag the higher you can mount them and allow different prop styles to be used. The ability to run a counter-rotation prop allows the boat to run more effeciently and flat along with gaining extra lift and effeciency in the water between the props.

You can rig boats to run home on one motor if your steering is set up and you can tilt the other one up ( gotta be fully powered to start with) I even know cats that will plane with one motor.

There is many factors in comparing setups and everyone talks about top speeds. Well who gives a pigs bumm aout that but what maters is around cruise speed effeciency. Top speed is a as useless as tits on a bull in 90% of situations and we all get sucked in talking about it by manufacturers. Torque to get on plane , flexible strong midrange and top end is a bonus you use now and again.

Concerns me that people with singles and single battery and single fuel tank somehow think they are bulletproof and immune and that someone should come collect em.. Tanks get holled , fuel can be bad or get water in it,batteries collapse fittings break, motors have mechanical or eletrical issues, props , debri and so on. Putting all you eggs in one basket. Hope you at least fork out the extra dough for a extra long radio aerial and a battery to keep it working so you can get assistance.

[Noelm]

not too sure there is less drag with the Motors mounted wider apart on a V hull, simply because the cav plate should be in the same place regardless of the configuration, too wide on a V creates a whole new set of problem in turns! anyone who has fitted twins regularly can attest to this. Anyone who bleats about running costs compared to the same HP single and so on has never owned twins.