Electric boat pods

[Interlude]

Does anyone know how the prop shaft seals on submerged electric pods hold up, or are made waterproof?

It seems to me that sail drive seals fail reasonably frequently, in my case twice in 17 years, with only 1000 engine hours. Checking the gearbox oil regularly can save the cogs, but ingress of sea water into the electric motor would be catastrophic, and even if they have alarms, the boat has to come out of the water.

I am not about to embark on an electric conversion at the moment, batterys will have to improve somwhat first. Just curious.

 

[penfold]

Induction motors generally have their coils sealed in resin, the principle risk is damage to motor bearings through grease wash out and unprotected iron and steel rusting. Provided there is a moisture detection system to alert operators that there's a leak and to take prompt action(lift out within days) permanent harm is unlikely.

 

[Poignard]

Induction motors generally have their coils sealed in resin, the principle risk is damage to motor bearings through grease wash out and unprotected iron and steel rusting. Provided there is a moisture detection system to alert operators that there's a leak and to take prompt action(lift out within days) permanent harm is unlikely.

Do you know if electric outboards with the motor in a pod (such as my Torqeedo 1103c) have similar protection?

 

[penfold]

No idea, if there is moisture detection it would be mentioned in the operator's manual.

 

[Moodysailor]

Does anyone know how the prop shaft seals on submerged electric pods hold up, or are made waterproof?

It seems to me that sail drive seals fail reasonably frequently, in my case twice in 17 years, with only 1000 engine hours. Checking the gearbox oil regularly can save the cogs, but ingress of sea water into the electric motor would be catastrophic, and even if they have alarms, the boat has to come out of the water.

I am not about to embark on an electric conversion at the moment, batterys will have to improve somwhat first. Just curious.

I would imagine that on an electric motor big enough to warrant a gearbox, the oil would be separated from the motor, so any water ingress would affect only the mechanical part and not the motor, much in the same way that your saildrive propshaft seal failing does not allow oil into your engine.

But, I know nothing of fact and am only speculating

 

[Pete7]

Does anyone know how the prop shaft seals on submerged electric pods hold up, or are made waterproof?

It seems to me that sail drive seals fail reasonably frequently, in my case twice in 17 years, with only 1000 engine hours. Checking the gearbox oil regularly can save the cogs, but ingress of sea water into the electric motor would be catastrophic, and even if they have alarms, the boat has to come out of the water.

Why would the pod seals be any different to other vessels with stern drives, outboards or as in your case a sail drive.

Was the cause of your two failures ever identified?

Pete

 

[lustyd]

Was the cause of your two failures ever identified?

I was thinking the same thing but I think the implication was that mechanical stuff could be saved after water ingress while electric would be a write off. This was addressed above and would seem to be less likely to result in failure so another win for electric power potentially. Now if only the initial purchase price would drop a bit!

 

[Interlude]

Re the seal failure on the SD20 shaft seal, in the first instance it was thought that a fishing line had damaged the shaft, which needed machining, in the second case no source found, just milky oil at annual service time, a very small quantity of seawater had entered.

I guess that a second seal in the pod, to seal oil from getting to the motor, would be less likely to fail than the sea water seal, but as there is no reduction or reverse gear, I don't even know if there is oil in the pod.

My take on this, failing any manufacturer information, is that boats planning to be offshore for extended trips would be far better off with shaft drives than either saildrives or submerged electric pods, and I would want an electric boat to have a shaft drive with the motor accessible from inside the boat, and any seawater ingress is visible and managed by bilge pumps, and shaft seals seem to be pretty good now.

 

[Tranona]

Saildrives are fine - thousands going offshore over the last 30 years or more. As you say they are vulnerable to fishing line getting in but this can be mostly prevented by fitting a rope cutter. Shaft drives are not trouble free - all systems where you have a shaft going from inside to outside the boat have weaknesses. Further down this page is a thread where a foreign body had got into the stern tube and damaged the lip seals in the shaft seal allowing water to get into the boat.

Regular posts over the years here about worn cutless bearings, loose P brackets, leaky shaft seals loose stern tubes and so on.