2 outboards alignment question

[Marceline]

Hi - we're buying a 24ft Bilge keel sailboat with main propulsion a 6hp outboard in a well before the rudder.

We've bought an ePropulsion Spirit 1.0 Evo to use with our tender, and we were planning on adding an adjustable outboard bracket on the transom with the idea we could lower it to try to recharge the Evo's battery if we're sailing at good speeds, but also that we could use that - rather than the petrol outboard - for situations where there is light winds/tides for some propulsion and not have to fire up/burn the petrol outboard. (also it'd be nice and quiet), and maybe even use in conjunction with the petrol outboard in the well if we need some extra push

So my main question is, with the main petrol propulsion in line with the rudder, would positioning the transom bracket then behind the rudder be a good/bad idea, or should I position the bracket offset to port or starboard ?


ps - should mention, we're only day sailing/short range and close to the coast etc

 

[VicS]

I'd mount it centrally because if offset the prop will most likely lift out of the water on one tack or the other making the "hydrogeneartion " feature ineffective.

I am intrigued by the claim that 1 kW is equivalent to 3 hp ......... 1.34 hp according to my maths!

 

[Marceline]

Thanks Vic and yeh that makes sense re the "hydrogeneartion" and tacking - I wonder if also having it directly behind the petrol means we 'might' get a bit of extra regeneration at times if we're using the petrol outboard/motorsailing.

We've no idea about if the Hp to 1kw as yet (as it's all new and the boats not ours yet, still in survey) - but we're hoping it'll more be towards the '3hp'. We're off out with the Spirit though next weekend with our Bic boat dinghy so looking forwards to seeing how it does

 

[Buck Turgidson]

Putting it inline is the best solution for hydro due to heel as stated above but the worst for power boost. Whether it benefits from prop wash would depend on many things because the flow is turbulent and will be offset when the rudder is not central so I wouldn't count on it.

 

[Tranona]

Thanks Vic and yeh that makes sense re the "hydrogeneartion" and tacking - I wonder if also having it directly behind the petrol means we 'might' get a bit of extra regeneration at times if we're using the petrol outboard/motorsailing.

We've no idea about if the Hp to 1kw as yet (as it's all new and the boats not ours yet, still in survey) - but we're hoping it'll more be towards the '3hp'. We're off out with the Spirit though next weekend with our Bic boat dinghy so looking forwards to seeing how it does

The equivalence has little to do with the output of the engine. It is not the engine that propels the boat but as its name implies the propeller. the spirit has a large slow turning propeller compared with a small fast turning propeller of a petrol outboard. It is not how much power you have but how you use it, and the Spirit will give you more than equivalent performance on your small dinghy as o 3hp petrol. Same on your cruiser , and probably a lot better. However do not expect much as shifting a couple of tons is very different from a dinghy. Expect maybe 2-3 knots in flat water. Don't hold your breath for any regeneration. This only works when you get up to 6 knots - way above your normal speed, plus the drag of the extra outboard will further reduce your sailing speed. Regeneration on these little electric outboards only make any sort of sense on lightweight planing sailboats or multihulls that can consistently sail over 6 knots.

 

[Marceline]

Thanks for the replies and really useful info thanks

 

[Marceline]

I'd been thinking about the above responses and just wanted to ask

if we were to get a 2nd electric motor for the well and not use the petrol at all (maybe an ePropulsion Navy but possibly another Spirit 1.0 if this seems ok pushing the boat in light conditions and for easier battery setup) and use these for propulsion only (and not really looking to get regen), would having the adjustable transom bracket offset to port or starboard be a better solution then (to avoid the turbulence if I'd placed it inline behind the well/rudder) ?

The boat is just under 1500kg.

 

[Supertramp]

I'd been thinking about the above responses and just wanted to ask

if we were to get a 2nd electric motor for the well and not use the petrol at all (maybe an ePropulsion Navy but possibly another Spirit 1.0 if this seems ok pushing the boat in light conditions and for easier battery setup) and use these for propulsion only (and not really looking to get regen), would having the adjustable transom bracket offset to port or starboard be a better solution then (to avoid the turbulence if I'd placed it inline behind the well/rudder) ?

The boat is just under 1500kg.

Years ago I stopped using a 2 stroke on my Eagle 525 and switched to a Torqeedo.

Several things learnt.

First was it became easy to lift the outboard out of the well and plug the hole giving much improved speed under sail. I also learnt to do everything under sail (small boat so easy anyway). Second was that the absolute power of the Torqeedo 1003 was no match for a petrol 2 stroke. Think headwind and waves. Third was the range which was fantastic at 2-3 knts but much less at 4 knts+. 13 miles of range could suddenly become 4 or 5 miles as conditions and speed changed. I bought a second(hand) battery which helped. And finally you had to ration carefully if away for several days although I did rig a primitive solar charger.

So think carefully about how and where you would use all electric on a small boat. Recharging takes longer than you might think and a better solution might be electric for a main unit and a small petrol as a reserve.

One final point. Depending on your well and engine, I wouldn't leave a Torqeedo sat in the water for days on end as there is only an o-ring keeping water out of the gear and motor unit.

 

[Marceline]

Many thanks - that's useful info as well - lots of food for thought thanks.

I think it'll be best we just go out with our boat as is and see how things are for next season with the petrol outboard and get used to the electric with our tender, then make a decision if/where to drill holes in the transom for when it comes out of the water in 2023. We can still swap them around if weather/tides/water is calm and try powering it with the ePropulsion in the well. Then we'll have a better idea. I guess I was just asking as we've a while before the boat goes in the water to have installed an extra outboard bracket.

Ok - thanks everyone + we'll put off putting more holes in our boat for a while

ps - the Eagle 525s look marvellous - hadn't seen those before