Ideas for converting from diesel inboard to electric propulsion for a dayboat.

[Andy Wood]

I've just been to the Southampton Boat Show where I talked to a few electric propulsion system suppliers about whether and how I could convert my Tofinou 7 from inboard diesel to electric. As I see it there are three options:

• Replace the current Yanmar 1GM10 with an electric motor and stick with the existing shaft mounted prop.
• Go for a pod-type motor which would have to fit between the aft end of the keg and rudder. This offers the benefit of freeing up space in the cockpit currently occupied by the engine, but would place the prop much closer to the rudder than at present.
• Devise a way of mounting an electric electric outboard on the side of the boat, as one boat I saw on show had done, but I reckon this would be cumbersome and take up a lot of my limited storage space.

Does anyone have any experience of retrofitting an electric propulsion system in a day boat of this kind? The suppliers I spoke too were keen come up with a solution but I'm reluctant to be a guinea pig! Any advice on 'best practice' gratefully received.

 

[wully1]

Advice No1. Get a BIG pot of money..

 

[geem]

Advice No1. Get a BIG pot of money..

Yep,
Really, Really big pot of money

 

[Chiara’s slave]

Yep,
Really, Really big pot of money

Depends how far he wants to motor. And in what conditions. If it’s windemere he might be able to make do with little more than a car battery. If it’s a sea loch, or the western solent, money would definitely be a governing factor. How far and where?

 

[Frogmogman]

I've just been to the Southampton Boat Show where I talked to a few electric propulsion system suppliers about whether and how I could convert my Tofinou 7 from inboard diesel to electric. As I see it there are three options:

• Replace the current Yanmar 1GM10 with an electric motor and stick with the existing shaft mounted prop.
• Go for a pod-type motor which would have to fit between the aft end of the keg and rudder. This offers the benefit of freeing up space in the cockpit currently occupied by the engine, but would place the prop much closer to the rudder than at present.
• Devise a way of mounting an electric electric outboard on the side of the boat, as one boat I saw on show had done, but I reckon this would be cumbersome and take up a lot of my limited storage space.

Does anyone have any experience of retrofitting an electric propulsion system in a day boat of this kind? The suppliers I spoke too were keen come up with a solution but I'm reluctant to be a guinea pig! Any advice on 'best practice' gratefully received.

My gut reaction would be to replace the engine with an electric motor driving through the existing shaft. No doubt the batteries could also be accommodated in the engine box. I guess it would also need a change of screw, due to the different power characteristics of an electric motor. Also easy to revert to original spec if required in the case of re-sale, for example).

I’d not inflict an outboard on something as pretty as a Tofinou if I could avoid it.

 

[Buck Turgidson]

Side mounted outboards are definitely a thing. Particularly on yachts with pretty sterns. Plenty of options for electric outboards and most can be broken into propulsion and separate battery for storage. If you can find "The sailing Fenchman" on YouTube, he uses an electric on his mini 650 that will even recharge itself through regen if you leave it mounted. This is the one area (along with tenders) where I think electric has a lot to offer.
p.s. Lovely boat!

 

[dunedin]

First define what you need in terms of
1) Engine power
2) Range under motor
3) Whether need ability to against tide or into strong headwinds (which dramatically reduces range)
Second assessment availability of electric charging sources at places likely to moor.

Then calculate
(a) motor size needed in kW, then
(b) battery size needed in kWh
That will allow approximating the costs. And then can assess installation options.

Sticking motor on existing shaft likely to be simplest, but likely need different prop.

 

[KevinV]

Funny, prompted by the thread about Spirit going all electric I had a bit of a Google - lots of suppliers of inboards/ sail drives out there, not one of whom publishes their prices. To me that reads as "overpriced at the moment".

 

[BB1]

I've just been to the Southampton Boat Show where I talked to a few electric propulsion system suppliers about whether and how I could convert my Tofinou 7 from inboard diesel to electric. As I see it there are three options:

• Replace the current Yanmar 1GM10 with an electric motor and stick with the existing shaft mounted prop.
• Go for a pod-type motor which would have to fit between the aft end of the keg and rudder. This offers the benefit of freeing up space in the cockpit currently occupied by the engine, but would place the prop much closer to the rudder than at present.
• Devise a way of mounting an electric electric outboard on the side of the boat, as one boat I saw on show had done, but I reckon this would be cumbersome and take up a lot of my limited storage space.

Does anyone have any experience of retrofitting an electric propulsion system in a day boat of this kind? The suppliers I spoke too were keen come up with a solution but I'm reluctant to be a guinea pig! Any advice on 'best practice' gratefully received.

Speak to Sam
The Electric Boat Company - Luxury self drive day boat hire and electric boat servicing specialists.

 

[Tranona]

I've just been to the Southampton Boat Show where I talked to a few electric propulsion system suppliers about whether and how I could convert my Tofinou 7 from inboard diesel to electric. As I see it there are three options:

• Replace the current Yanmar 1GM10 with an electric motor and stick with the existing shaft mounted prop.
• Go for a pod-type motor which would have to fit between the aft end of the keg and rudder. This offers the benefit of freeing up space in the cockpit currently occupied by the engine, but would place the prop much closer to the rudder than at present.
• Devise a way of mounting an electric electric outboard on the side of the boat, as one boat I saw on show had done, but I reckon this would be cumbersome and take up a lot of my limited storage space.

Does anyone have any experience of retrofitting an electric propulsion system in a day boat of this kind? The suppliers I spoke too were keen come up with a solution but I'm reluctant to be a guinea pig! Any advice on 'best practice' gratefully received.

Forget the outboard. Choice is pod or motor using your existing sterngear. The trend is towards pod on new boats like yours and that would be first choice but I suspect looking at the drawings of the underwater body you may need to carry out serious mods to the end of the deadwood to make space for the pod drive in front of the rudder. Worth looking at how Cornish Crabbers have done it in the Shrimper.

Think you have to accept if you are going electric on a boat that was designed for a diesel inboard you will encounter problems and the simplest way is to just replace the Yanmar with an appropriate electric motor in the same location. This, however is a sub optimal solution as you don't get the benefits of packaging and performance that a pod can provide.

 

[dunedin]

Funny, prompted by the thread about Spirit going all electric I had a bit of a Google - lots of suppliers of inboards/ sail drives out there, not one of whom publishes their prices. To me that reads as "overpriced at the moment".

Oceanvolt quote prices on their sites.
Electric drives are very cheap. It’s the batteries plus the rest of the system (controllers, chargers, props etc) that push the prices up.
And without doing the calculations (eg on range needed) and configurations cannot estimate a price

 

[bignick]

Have a look at the “Sailing Uma“ videos on YouTube.
They converted their yacht from diesel to electric propulsion.
Originally they started with a motor from a golf cart and retained the shaft drive, but over the years they went to a secondhand Oceanvolt system and eventually to a new Oceanvolt. Lots of useful info there.

 

[Kelpie]

Have a look at the “Sailing Uma“ videos on YouTube.
They converted their yacht from diesel to electric propulsion.
Originally they started with a motor from a golf cart and retained the shaft drive, but over the years they went to a secondhand Oceanvolt system and eventually to a new Oceanvolt. Lots of useful info there.

I'm always very impressed by what Uma have done. The change to a new Oceanvolt was because the company made them an offer they couldn't refuse, IIRC.

 

[Frogmogman]

I do think a lot of you are missing the point.

The OP is talking about a 7m dayboat which can sail well in quite light airs. The requirement for a motor will be for getting in and out of harbour, or a push when the wind dies completely. He’s not looking to cross oceans; I’d say a dayboat that can be hooked up to shore power is a perfect candidate for an electric installation.

 

[bignick]

Yes, great advertising for Oceanvolt as Uma are huge advocates of electric propulsion on boats.

They had problems with their secondhand one, so replaced with new,, and you don’t know if there was a clause in whatever agreement they were offered about negative publicity thereafter. Still some really good info on the installation process and they do seem to be as unbiased as it’s possible to be when someone gives you a huge discount.

 

[bignick]

I do think a lot of you are missing the point.

The OP is talking about a 7m dayboat which can sail well in quite light airs. The requirement for a motor will be for getting in and out of harbour, or a push when the wind dies completely. He’s not looking to cross oceans; I’d say a dayboat that can be hooked up to shore power is a perfect candidate for an electric installation.

I agree - the boat is a perfect candidate, but not everyone wants to mess about with electric outboards. That said, I did see pics of a really neat Torqeedo installation on a Fareast 19, which had a remote throttle and batteries in the boat, with a big multi plug

Is a Tofinou 7 a trailer sailer?
// Actually it’s a shaft drive and should be kept that way, so an OV system would be much better.

 

[Frogmogman]

I agree - the boat is a perfect candidate, but not everyone wants to mess about with electric outboards. That said, I did see pics of a really neat Torqeedo installation on a Fareast 19, which had a remote throttle and batteries in the boat, with a big multi plug

Is a Tofinou 7 a trailer sailer?

I was thinking of electric motor replacing engine rather than outboard.

No reason why it wouldn’t work as a trailer sailer. Centreboard, displacement 1.3 tonnes, beam below 2,5 m…..

lovely boats btw

 

[Andy Wood]

Thanks for your responses. Indeed, the boat is an out-and-out day sailer based in Weymouth, and I am unlikely to venture far out of Weymouth Bay. I doubt I would go beyond St Alban's Head and certainly not round Portland Bill so I'm not going to be in a situation where I'm going to need to punch a strong tide. So getting in and out of Weymouth harbour and maybe getting back from Lulworth, say, if the wind falls away completely is about all I will need an engine for.
The consensus view seems to be to stick with the shaft driven prop, so my inclination is to keep my so-far trusty diesel for the time being; after all, I'm not exactly leaving a massive carbon footprint. If and when the engine needs replacement I can go for an electric replacement, but doing so now would be little more than a 'vanity project'!

 

[DownWest]

Also, yours is a classic situation where an O/B off the side would work, as you only need it when the wind fails, so the problems with heeling and pitching don't apply.

 

[skua164]

I'm in Argyll and have a Rustler 24. In 2021 replaced a 2T Tohatsu with a Long Shaft E propulsion Spirit. I can sail on and off the Mooring and its purely used to get back if the Wind dies to nothing. It's side mounted with the leg being light to lift on to the bracket and then attach the Battery ( which floats accounding to the Blurb ....albeit I don't intend to try that out !).

On the Mooring I usually leave the Leg on Board and just take the battery back for charging.