steerable saildrive

[Zonker]

Could you dock with the outboard only ?

Not happily. My wife often docked with diesel only because as I said the outboard didn't like to sit for 6 months and wouldn't idle well or run without stalling.

The tiny low speed jets would get clogged. I wasn't smart enough to use fuel stabilizer.

Lots of Prouts and some Gemini cats used a steerable single extended leg Sillette drives on centerline. Pretty heavy but fairly robust. Not nearly as good as twin engines but saves on the cost/weight of twin diesels.

 

[Zonker]

Hybrid (generator plus e-propulsion) is heavier in total weight, riskier (lightning apparently can take out both e-drives) and more difficult to mantain. Plus either less HP or less range when motoring.

"She is equipped with a custom plug-in hybrid propulsion system that silently powers two electric drives and all the appliances and electronics on board. While sailing, the batteries are being recharged through re-generation, so the generator, if needed at all, only runs for very short periods. This means her state-of-the-art technologies maximize the guest’s enjoyment while minimizing the boat’s impact on the environment."

When I see hybrids being touted as the next great thing I always ask "what problem are you trying to solve". With this configuration you will always be limited by battery capacity. So you can probably motor for 3 or 5 hours before killing the battery. Then the generator fires up, making electricity to turn an electric motor, which is less efficient than just connecting a diesel to a prop. So... for a boat that mostly cruises very locally 5 hours range on battery may be OK, but for longer distances that isn't very fun.

 

[LiquidSun]

There are different types of hybrid, not just series ( generator plus e-propulsion) Parallel systems seem more common in pleasure craft and provide redundancy.

Heat Exchanger Hybrid Propulsion - Marine Propulsion Engines Beta Marine

betamarine.co.uk

As I see it, the advantage of hybrids is you can keep the diesel the sweet part of the fuel efficiency curve by either generating electricity or adding electric torque while motoring.

You can also use electric propulsion for short runs like pulling up anchor and leaving anchoring... saving wear and tear & consumption of running a cold diesel.

If you have excess solar generation you can use that for propulsion or to add propulsion. The weight & space saved by not having a separate generator can be used for batteries.

There are certainly cases where hybrid doesn't increase efficancy and ways a user can make it less efficient if used unintelligently. I feel hybrids make the most sense on Catamaran's where there is more deck space for solar generation.

 

[he b gb]

Not happily. My wife often docked with diesel only because as I said the outboard didn't like to sit for 6 months and wouldn't idle well or run without stalling.

The tiny low speed jets would get clogged. I wasn't smart enough to use fuel stabilizer.

Lots of Prouts and some Gemini cats used a steerable single extended leg Sillette drives on centerline. Pretty heavy but fairly robust. Not nearly as good as twin engines but saves on the cost/weight of twin diesels.

View attachment 573427

I have one of these on my cat running of a 28hp diesel,mainly due to wanting to keep weight down and keeping the prop out of the water but also for saving the expense and maintenance issues of two diesels. I can cruise at around 6 kts.
Do I like it? not really, it’s super noisy so I tend to use the engine as little as possible. The leg in the photo had straight cut gears which I was told was the reason for the noise plus it was already 25 years old when I installed it so about 4 years ago I decided to replace it with the new model which has radially cut gears. It cost $7,000 to import from England so was an expensive exercise that I was willing to do for quieter motoring. Was very disappointed 😢 when it made bugger all noise

difference.
I’ve done some sailing on a mate‘s cat that has a 4 stroke outboard and can’t believe how quiet and vibration free it is when motoring but I really like the safety side and economic use of diesel fuel.

 

[Trovão]

There are different types of hybrid, not just series ( generator plus e-propulsion) Parallel systems seem more common in pleasure craft and provide redundancy.

Heat Exchanger Hybrid Propulsion - Marine Propulsion Engines Beta Marine

betamarine.co.uk

As I see it, the advantage of hybrids is you can keep the diesel the sweet part of the fuel efficiency curve by either generating electricity or adding electric torque while motoring.

You can also use electric propulsion for short runs like pulling up anchor and leaving anchoring... saving wear and tear & consumption of running a cold diesel.

If you have excess solar generation you can use that for propulsion or to add propulsion. The weight & space saved by not having a separate generator can be used for batteries.

There are certainly cases where hybrid doesn't increase efficancy and ways a user can make it less efficient if used unintelligently. I feel hybrids make the most sense on Catamaran's where there is more deck space for solar generation.

AFAIK, this is the system Leo is installing on Tally-Ho.

 

[CapDave]

Actually my interest might be well aligned with the sailors. I never use the second engine except for manouvering, so why not do without and add a retractable bowthruster to help in tight places ? Catamaran size is 60’ for 18 tons fully loaded.
Less weight, less drag, less maintenance.
I am just concerned I might be overlooking some cons …

@mpenman might weigh in, he has a bow thruster and twins on his Atlantic 72. He says he put in the biggest bowthruster that fit, and it's not enough help. I don't know the details of his installation, but it's likely some combination of the geometry details @Zonker pointed to that are the trouble.

I think if you're comfortable with a single prime mover (personally I like the redundancy, as well as the rarely-used extra power, of twins) then the best choice might be to replace one diesel with an electric drive train that is big enough for maneuvering. And you can likely hydrogenerate with it too, though I've always found the noise and vibration of hydrogeneration unacceptable myself.

I think this plays to the strengths/weaknesses of electric propulsion pretty well, and probably saves you at least 300 lbs and one full set of diesel spares and maintenance. Likely not too cost effective, but lightweighting is expensive, $10/lb is just table stakes and up from there.

EDIT - a retractable thruster might duck some of the geometry issues, but then you still have to supply a lot of amps many feet from the batteries, usually people use (heavy, far forward) dedicated batteries. And if you occasionally regret the maintenance overhead of a diesel, wait until you own a retractable thruster.....

 

[jmh2002]

AFAIK, this is the system Leo is installing on Tally-Ho.

Yes that's right. It is also the system that HH Catamarans will be using, as well as Antares Catamarans, and a few other manufacturers too.

The Hybrid Marine system offers multiple different modes of use, which may or may not be of benefit depending on the boat and how and where you will use it.

I think the most benefit is gained from this type of system when installed on a performance catamaran, where you won't motor a lot but still want diesel for backup and the occasions when longer motoring range is required.

Weight wise, the electric motor portion of the Hybrid Marine system - which also generates electricity for charging in an alternator type fashion - doesn't add a significant amount of weight.

The batteries normally installed together with such a system do add extra weight of course - especially when compared to a simple boat with one diesel and not much battery capacity.

But is that how many catamarans are setup these days? In most cases I would say no.

In general many catamarans are going for large LiPo battery banks together with large Solar installations - regardless of what their propulsion system is.

So the weight of the battery bank may exist anyway. If it does, it might be advantageous to be able make more use of it, with some propulsion at times.

There can also be a substantial weight offset if the boat would normally have a generator, that can be removed, or not fitted in the first place.

The Hybrid Marine system is also able to charge via regen. Realistically probably 500-1000W total from both shafts for a normal performance cruising cat.

That may not sound like a lot - but it will add up on a passage, which is when there is the most energy demand. 12-24kW into the battery bank over 24 hours is not insignificant.

Finally, the Hybrid Marine system is still just a standard diesel engine. If any of the electronic wizardry part of the Hybrid package fails the diesel engine still retains it's direct drive to the shaft to provide propulsion.

Really the only specific negative point to this system is the extra cost.

If budget is an concern, skip the additional benefit of some electric propulsion and regen and just install diesels with conventional big alternators.

If you want the lightest possible system, that is another question again, and needs to be looked at in total with the whole boat:

- minimalist comforts and therefore electrical system
- minimal battery bank required
- only a light simple propulsion and battery charging system needed

But many people who start out with a minimalist system like that often end up adding more and more to it over time.

 

[Zonker]

you know one good $/lb? - inflatable fenders!

Polyform F6 - 11" x 42" good quality conventional solid PVC fender - 4.2 kg/ $195 Defender

Aere 12" x 42" inflatable PVC - ~1 kg/$250

AERÉ 12" Inflatable Boat Fenders | AERE Docking Solutions

AERÉ 12" Diameter Fenders - Made from reinforced materials with Stainless Steel "D" ring on each end. Versatile and space-saving solution for boating needs.

aeredockingsolutions.com

Save 3 kg (6.6 lbs) for $55 = $8 / lb x say 6 fenders

 

[jmh2002]

you know one good $/lb? - inflatable fenders!

Definitely

Plus they save more space too.

And it means you can probably carry a couple of extra large 'storm fenders' too, without worrying so much about how to store them.

 

[longy]

I believe there are quite a few big cats with bow thrusters. They will be using retractable units to get far enuff under the water (& no drag) I know the big Kinetic cat had one fitted about a year after launch. Med mooring ability is important for those big cats

 

[jmh2002]

I believe there are quite a few big cats with bow thrusters. They will be using retractable units to get far enuff under the water (& no drag) I know the big Kinetic cat had one fitted about a year after launch. Med mooring ability is important for those big cats

Yes, whilst in theory I agree with the normal comment of not needing bow thrusters in many boats, there are some locations where mooring and docking situations are much tighter, and preclude the use of a lot of power, helm over, walk the boat, etc, or even other spring line docking techniques.

Sometimes you have literally centimetres / inches / nothing between the two other boats that you must dock between.

You also have much more need to 'hover' in position while anchors are laid, fixed mooring lines are picked up, etc, etc.

 

[mpenman]

@CapDave , hah, we have a retractable thruster. SRVP100, which was the biggest I could get in the boat to have it far enough forward to make a difference. Our hulls are skinny up front and v shaped, so tough to get a thruster positioned correctly. I think it's about 250lbs of thrust, whatever that means. Kinda like two people pushing on the boat from a dock is what it feels like to me .

I have given some thought to removing it and just glassing in the hull and take back the space. Thruster is not that heavy at about 100 lbs and is retractable. All that being said it aids some, but when it's blowing more than 15, my hulls get blown around very quickly as the boat is light and my props are way back there and the freeboard up front is immense.

I don't have enough experience with it around the docks to give it a yay or nay yet. I had a similar experience to you at NSY with damn concrete docks. Why not install a track that you slide in slender foam fenders. It's all fine when the winds are down, but once they pipe up, you have to come in hot. Why don't they just build in some protection........and concrete makes a lovely mess with fiberglass and paint.

For us we have to keep speed around 4 knots or we start to move sideways and that's with the boards down. At Shelter it was blowing a nice 18-20 directly perpendicular to the fairway. Had to come in hot, pivot and stick it in the slip with the fingers only being about 40 feet in length. Just way too little margin for error IMHO.

We have the big Fendertex fenders and we really like them. They're 24inches in diameter. When you're done, they fold down to almost nothing and are very very light. Had them hold up in 50knots against the dock in Newport. Very strong.

Electric engines are not there yet. We don't motor much, but there is comfort in knowing we can motor a fair way if we have enough go go juice in the tanks. We have 5.4KW of solar and it's almost enough!!!!!! Hybrid adds complexity that is not needed on a boat being attacked daily by seawater.

I'm not sold on hydrogens for cruising boats for a number of reasons, but that's for another thread.

 

[jmh2002]

Thanks @mpenman all good info regarding the experience with your boat

Electric engines are not there yet. We don't motor much, but there is comfort in knowing we can motor a fair way if we have enough go go juice in the tanks. We have 5.4KW of solar and it's almost enough!!!!!! Hybrid adds complexity that is not needed on a boat being attacked daily by seawater.

I'm not sold on hydrogens for cruising boats for a number of reasons, but that's for another thread.

One point I do disagree with you on though is that Hybrid 'adds extra complexity', at least specifically as far as the Hybrid Marine system is concerned.

That's because I look at their system as being not much different to a normal diesel engine with a large alternator setup.

It is effectively a large alternator, belt driven from the engine, just the same, and working in reverse to drive the shaft when needed. A simple mechanical clutch on the shaft is really the only other significant difference. And that can be locked manually in case of a failure.

Yes there are some added electronics, but to be fair a conventional large alternator and LiPo battery system has similar electronics to control charging and manage batteries too, so not a lot of difference there either.

This is all quite different compared to other "Hybrid Systems" and certainly very far away from the system posted above on Moonwave.

The Hybrid Marine system is really quite simple and robust in that respect.
And as I mentioned, a failure of the Hybrid / Electric side doesn't prevent the diesel from working and providing propulsion (or vice versa).

In my opinion that's a huge benefit of parallel systems like this, compared to other series systems that have a separate electric motor and a separate generator. Yes, electric motors are generally very reliable but if it fails in a remote location good luck getting it fixed. I think worse still if it's an electric motor pod and saildrive combination like on Moonwave.

And if the (normally only one) generator fails there is no charging or propulsion at all (except from the batteries and solar).

Whereas a conventional shaft and prop are normally the most reliable part of a propulsion system, so having two separate methods to turn the shaft is a really nice benefit as far as redundancy.

I will agree however that one needs to carefully assess if the extra benefits of such a system - basically the Electric Propulsion and Regen - are worth the additional cost, for how the boat will be used.

But everything else is every similar to any other boat with diesels, large alternators, and a large LiPo battery system.

For some people the extra cost may worth it. Some people really want to avoid running a diesel engine as much as possible, but recognise that they still need diesel backup on a long distance live aboard cruising boat.

On your boat, as you said you already don't motor much, and such a system would probably mean that you almost don't need to motor (with the diesel) at all.

Some people want that.

The Hybrid Marine system is a way to have it without many of the downsides of other hybrid systems.

Personally it's the redundancy of this setup that I like best. If one diesel engine is not working for some reason it's still possible to manoeuvre using both props by using the bad side with the electric motor driving the shaft, and the good side with the working diesel (or even just both sides on electric depending on what the situation is). And vice versa if it's one of the electric motors that's not working.

On a monohull that's an even better backup because normally there is only one diesel engine in the first place.

 

[CapDave]

you know one good $/lb? - inflatable fenders!

Polyform F6 - 11" x 42" good quality conventional solid PVC fender - 4.2 kg/ $195 Defender

Aere 12" x 42" inflatable PVC - ~1 kg/$250

AERÉ 12" Inflatable Boat Fenders | AERE Docking Solutions

AERÉ 12" Diameter Fenders - Made from reinforced materials with Stainless Steel "D" ring on each end. Versatile and space-saving solution for boating needs.

aeredockingsolutions.com

Save 3 kg (6.6 lbs) for $55 = $8 / lb x say 6 fenders

Got 6 of them....

 

[PIL66 - XL2]

Our 40' cat had a single 27 HP diesel in 1 hull, and a Yamaha 9.9 high thrust outboard against the back beam on the other hull. Worked very well for tight quarters movements. Except for our life (99% at anchor where we didn't use the outboard for anchoring) - the outboard suffered from lack of use. The outboard was a good backup and would push the boat at ~ 5 knots in calm weather. And at about $4000 it's about the same price as a bow thruster. It's not for everybody. Lots of people like 2 x diesels.

You're not going to fit a 10HP bow thruster in a typical 40' cat so the outboard gives you better performance and no hole in the bow.

could you double up your tender on davits to be the 9.9 hi thrust you use to maneuver...?

Could you dock with the outboard only ?
In other words, do you think that a single steerable saildrive would be sufficient for docking ?

I only have a center pod with a 20hp honda hi thrust motor but it is steerable connecting to my tillers (boat is 42ft but only weighs 3.2 ton) I do all close maneuvering going backwards and use the wind with boards down... not for beginners
Had a 36ft 6ton Chamberland with 2 x volvo 29hp sail drive... beam is 20ft so never needed bow thrusters and don't like them for cats in any size ...
I guess if i had all the money in the world i'd have 2 x motors and thrusters like all my stink boat friends for ease.
I am a fan of 4 stroke drop down motors like the Stealth Asia cat boats have for efficiency and cost

you know one good $/lb? - inflatable fenders!

Polyform F6 - 11" x 42" good quality conventional solid PVC fender - 4.2 kg/ $195 Defender

Aere 12" x 42" inflatable PVC - ~1 kg/$250

AERÉ 12" Inflatable Boat Fenders | AERE Docking Solutions

AERÉ 12" Diameter Fenders - Made from reinforced materials with Stainless Steel "D" ring on each end. Versatile and space-saving solution for boating needs.

aeredockingsolutions.com

Save 3 kg (6.6 lbs) for $55 = $8 / lb x say 6 fenders

Inflatable fenders are the best.... been using them for years for boats up to 100ft

 

[Zonker]

could you double up your tender on davits to be the 9.9 hi thrust you use to maneuver...?

My dinghy motor was a 15 HP 2 stroke, 15" shaft. Weighed about 85 lbs

A 4 stroke 25" shaft 9.9 high thrust is about 120 lbs.

Huge difference (a) when dragging the tender up the beach (b) launching in the surf you really want the shortest shaft possible to get going fast and not get the dinghy right into the break zone.

Also swapping back and forth and adding remote control cables etc from the dinghy would be a huge headache. The dinghy motor saw daily use. The "maneuvering" engine saw use every 6 months.

 

[sbpoint]

The Hybrid Marine system seems like a no brainer for a new build. Propulsion redundancy, skip the generator (parts & maintenance), regen without hanging and storing some extra contraption off the stern, no sail drive (seals&oil&haulouts&crap), and less daily idle hours on the engines as you putts around the marina and anchorage (few hundred per year at least for an active cruising boat). Integral removes the genset but that’s about it.

$$ and getting your builder of choice to install shafts appear to be the only downsides.

 

[Happy Wolf]

the hybrid solution sounds interesting. you could have a diesel-hybrid in one hull and an Oceanvolt SD in the other hull. the latter would be fueled by a common battery bank that in turn gets its power from the hybrid’s generator, solar panels and the SD’s hydrogeneration.
as the e-propulsion is used for docking only, it won’t kill your battery bank. for motoring you use the diesel direct propulsion.

 

[jmh2002]

the hybrid solution sounds interesting. you could have a diesel-hybrid in one hull and an Oceanvolt SD in the other hull. the latter would be fueled by a common battery bank that in turn gets its power from the hybrid’s generator, solar panels and the SD’s hydrogeneration.
as the e-propulsion is used for docking only, it won’t kill your battery bank. for motoring you use the diesel direct propulsion.

Yes, this is a commonly accepted 'lightweight' option which also offsets some of the weight of the larger battery bank in smaller catamarans (or enables you to put more of the weight into more batteries, instead of into another diesel engine).

Of course it does mean that you lose some redundancy by only having one diesel engine, but that may be acceptable to some people.

Also, you don't need to have a sail drive on the other side, you could also still have a shaft with an electric motor.

However the fancy new sail drives with the automatically adjustable pitch props may be attractive as far as providing better regen capability - but probably at the cost of less reliability or less ability to be repaired in a remote location when compared to a standard fixed shaft.

The fixed shaft should of course have a feathering 3 blade prop, and the various 'auto prop' types seem to take best advantage as they change their pitch in forward and reverse - ie: when used for regen.

Finally, this is also more fuel efficient, because you are only running one diesel when motoring, at a more optimised load.

For a long distance live aboard cruising yacht I personally prefer the idea of the twin hybrid installation so that there is complete redundancy on both sides, and a simple matching installation, but I can also see why these other combinations may be attractive to other people, or in different situations.

 

[Happy Wolf]

thank you all for the constructive input