What size Auxiliary Outboard

[Chris B]

We have just bought a Marex 280. 29' semi displacement motor boat about 3Te. Currently on Thames but we are planning to take on some coastal trips, As it is single engine, for safety we want to fit an auxiliary outboard. Can anyone recommend from experience what size we need. Don't want to go too large but want it to be able to get us home without struggling to much if there is a bit of wind or tide.

Regards

Chris

 

[Bandit]

To push a boat of that size I would have thought a 15 to 20hp with a low pitch prop to give more thrust. In anything other than perfect conditions it would be very difficult to drive a boat like this with an outboard mounted on the swim platform .

Is she outdrive or shaft and rudder? If the is shaft and rudder she may steer ok on the helm if outdrive forget it, you would have to steer from the swim platform.

However assuming the engine is a diesel, I would spend my money on servicing, getting to know the engine and fuel system well, fuel cleaning and treatment, a rope cutter, an engine owners course, and life raft, flares, hh VHF etc. There are a lot of single engine leisure boats around without a standby outboard.

 

[Canopy Locked]

To push a boat of that size I would have thought a 15 to 20hp with a low pitch prop to give more thrust. In anything other than perfect conditions it would be very difficult to drive a boat like this with an outboard mounted on the swim platform .

Is she outdrive or shaft and rudder? If the is shaft and rudder she may steer ok on the helm if outdrive forget it, you would have to steer from the swim platform.

However assuming the engine is a diesel, I would spend my money on servicing, getting to know the engine and fuel system well, fuel cleaning and treatment, a rope cutter, an engine owners course, and life raft, flares, hh VHF etc. There are a lot of single engine leisure boats around without a standby outboard.

Aux outboard is a total waste of time. I had a Hardy 24 several years ago and the previous owner had fitted a 15hp Honda Aux to the swim platform and he'd spend a load on remote steering. Tried it out on the clyde where the boat was berthed - worked great. tried it again one day in the North Sea - not flat calm - just a normal day - totally useless - could not move the boat into the swell as the o/b kept coming out of the water. Do as the other poster suggested - save your money, service the engine properly - perhaps invest in a by-pass fuel filter system so you can change filters easily at sea.

 

[ontheplane]

Sadly I kind of have to agree.

To move a 28' boat on a flat calm river I would think a 15-20hp bigfoot (lower pitch prop, low gearing designed for thrust not speed) would do it.

On a swell or in strong wind/current I think you'd need more like a 40-60hp to be even remotely effective - which isn't really practical to mount on a swim platform.

The only benefit of fitting say a 15hp on the transom would be to minimise drift danger - in other words you need to completely forget "but want it to be able to get us home without struggling to much if there is a bit of wind or tide." that is simply never going to happen without fitting something like a 60hp bigfoot. What you CAN do with a 15hp would be to be able to make the boat work WITH the wind and tide to achieve a landfall or to keep you off a rock or something. So if without an outboard, you would be blown and drift onto a row of rocks, you may be able to point the boat at 90deg to the tide, and push it far enough to miss them. Similarly, if you are being blown out to sea, and would simply drift mid-channel, you may be able to influence the drift so that you end up on a beach / sandbank, or even to a harbour entrance further down the coast.

It may also help you "hold station" - so in light winds and tides, it may well be able to keep you nearer where you need to be until help arrives.

But fight against a wind / tide with a boat of that size, you'll need a LOT of thrust, which a small outboard with a small prop can't supply.

 

[Chris B]

Thanks for the comments Guys

We are doing all the look after your main engine things, but your comments re getting reliable drive from an outboard are certainly interesting, We have conventional prop and rudder, so hopefully could steer, Think I will borrow an outboard to try out before spending good money.

Regards

Chris

 

[Scubadoo]

Consider joining SeaStart, but check coverage first for your area. Excellent service and they are quick to respond, they have fast ribs and shoreside support to discuss any engine problems etc all for around £125 pa.