Catamarans: better with an engine in each hull, or a retractable sail-drive?

I spent most of last night looking at various reports of the Heavenly Twins. One of those very distinctive, smaller boats which I'd somehow never taken time to investigate. So far in my researches, I haven't heard a single word against it. Anybody know if it's still built?
 
dancrane said:
I spent most of last night looking at various reports of the Heavenly Twins. One of those very distinctive, smaller boats which I'd somehow never taken time to investigate. So far in my researches, I haven't heard a single word against it. Anybody know if it's still built?
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Don't make them now but a slightly extended version, Summer Twins, is still made down in Devon... http://www.multihullcentre.co.uk/mhcsummer.htm The company is run by the original designer's son. Chartered a Star Twins (34ft) from them many years ago which is what got me interested in catamarans.
 
I see the Heavenly Twins' auxilliary may be a central diesel, powering twin hydraulic drives in the hulls...or twin Yanmar 1GM10s. The idea of a pair of sturdy little diesel donkeys aboard a 27-footer set me thinking about other Heavenly Twins characterisitics...

...namely the fact that her slender hulls readily exceed displacement hull speed...so: suppose one replaced the 2 x 9hp, with treble the Yanmar power, from only double the weight...(2 x 3GM30)...

...with the right propellors, this cute little catamaran (which is also roomy & tough enough to go global) might prove quite a motorsailing flier, too. John Passmore reckoned 13 knots under sail, with a serious wind astern. But I s'pose weight of fuel would become an issue... :(
 
dan,

I knew a couple very well who bought a Heavenly Twins and put it on a mooring next to me; the thing wouldn't do more than 4 knots if you strapped a rocket engine to it or dropped it out of an aeroplane, it was awful, a demonstration of why displacement hulls don't work on cats.

Sort of nice accomodation if one is into kinky hide and seek I suppose, otherwise a lemon, they quickly sold it. :rolleyes:
 
Damn! Thought I'd found my ideal, for a minute there. :rolleyes:

Thanks for the low-down though. I'd started to think it must be some kind of subtle perfection, albeit in a funny costume.
 
Seajet said:
dan,

I knew a couple very well who bought a Heavenly Twins and put it on a mooring next to me; the thing wouldn't do more than 4 knots if you strapped a rocket engine to it or dropped it out of an aeroplane, it was awful, a demonstration of why displacement hulls don't work on cats.

Sort of nice accomodation if one is into kinky hide and seek I suppose, otherwise a lemon, they quickly sold it. :rolleyes:
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They made 475 Heavenly Twins which suggests it may have been rather popular! Often overloaded they suffer badly from too much weight and a couple of donks with associated tanks, batteries and stern gear won't help. The most we got from ours under sail was 11 knots and in a blow she would move but they are rather slow. A few have circumnavigated but what they excel at is coastal pottering. Oodles of space, safe as anything and they only need a 10hp outboard to make them shift at 5knots at 75% revs. What they're rubbish at is long sailing passages where the speed thing gets irritating, large occupancy and round the cans racing. Though a HT regularly wins the small multi category in the RTIR, to do so they strip her of all gear. Really nice cruising yacht, no flyer but a peach for pottering.
 
Dan,

I have a certain amount of time for the flexible lashed idea of Wharrams, but wouldn't fancy being in one in a gale let alone storm, if people want to prove the idea they can carry the cameras and instrumentation ! :eek:

There are a lot of good sailing boats around if you don't mind working on them ( personally I'd enjoy it and I'd want to know my boat end to end anyway so it's ideal ).

Or are you still looking at dinghies ?

An early type A22 goes like a rocket if kept light, may not be fancy but you can easily sleep aboard before the return match...
 
I confess, I'm only looking at dinghies for the forseeable future. And even though right now might be the cheapest time of year to buy, I'm mostly only looking at the giveaways there, too!

All the same, I'm fascinated by clever use of space, and smart alternatives to drab design aboard all yachts, all sizes.

That Heavenly Twins surely packed a lot into 27ft. I like the deep cockpit area too, I saw a version with a wheelhouse built on top! Must have been roomier that the average 36 ft mono. Pity about the performance.
 
boatmike said:
I have owned both. Frankly the sillette legs are a bunch of **** engineering wise. They are always in need of service regarding pivot points and locking mechanism and are very very noisy. The only advantage of the damn things is that you can raise them when not sailing and if you get a rope around the prop. However, be warned that I once got a rope around a prop and it tore the leg completely off its yoke. The castings are very poor and pourus and break easily! Twin engines are far better but like all sail drives you need to be assured that the rubber gaskets are in good condition and there is no water getting in the engine bay because it can corrode the sump and cause big oil leaks. For manouvering the twin engine configuration is also far better and you dont need contra rotating props with them that far apart. The ideal set up IMHO is twin engines with brunton autoprops. Perfect!!
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Prouts fitted Volvo legs which were very robust.
 
25931 said:
Prouts fitted Volvo legs which were very robust.
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You are either wrong or have totally misunderstood the previous posts. ALL Prouts with centre engines had Sillette lifting legs. With TWIN engines the saildrives were either Volvo or other makes depending on what engines were fitted and what model Prout we are talking about.
 
I had a conversation with Darren Newton at DazCat about a similar subject. I was wondering why not use an outboard engine on each hull? But they go for two small inboard diesel engines because
1) it keeps the weight inboard and lower down
2) the installation is more secure, robust and simpler
 
snowleopard said:
Yes!

A twin-engine setup is vastly superior for several reasons:

  • With saildrives and folding props the extra drag of a second gear leg is negligible.
  • Two props set a long way apart (in my case 17 ft) mean you can turn in your own length. You can also make the boat go sideways. A steerable centre leg does help but will never be as good as twin props.
  • Props slung under the hulls never cavitate so you can motor to windward in any weather. A central leg will pop out from time to time however deep it is.
  • Twin engines mean there is another to use if one fails.
  • For economical motoring or motor-sailing you can run on one engine (the windward one when motor-sailing)
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Agree with all this plus you have two battery banks independently charged and which can be cross linked if need be.

On a cat like mine a steerable single outboard is OK for weight saving and reduced drag (half a knot plus difference leg up to leg down) but on a Prout, twin engines are hugely preferable - and the Prout outdrive set-up is pretty dire
 
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I must have been half-asleep for three weeks...the point I'd meant to make latterly, was that a Heavenly Twins I saw for sale, has a pretty big (20hp) centrally-mounted diesel, which powers a pair of hydraulic drives, one in each hull.

View attachment 22640

So...great engine access (it's in the cockpit), no vulnerable outdrive-leg, full manoeuvrability of a folding propellor in each hull, but a lot less weight than a pair of smaller diesels. Plus this option frees the considerable hull-space the diesels take up in twin engine versions...

...I'm just wondering how effective/efficient/reliable the hydraulic drive is? They're certainly compact. Not common, though.
 
Mike,

Friend of mine had an early Snowgoose 34 and it had a Volvo outdrive fitted - plus Volvo engine. From memory length of leg was not as long as the Sillette. This boat is called Chefren and was fitted with a Sillette outdrive by the next owner.

Chefren originally had an experimental rig on it called "Pyramid Rig". It fell down and a standard Snowgoose 34 rig was fitted just before my friend bought it.

Bob
 
I used to own a Banshee with a Kubuta 40hp turbo diesel mounted in the cockpit driving two hydraulic outboard legs which could be lifted when sailing. The system worked well, weight was more than a two Yamaha 9.9s but less than twin diesel in each hull. With our installation the diesel was exposed being in the cockpit only covered by a composite cover which meant more maintenance and noise. The hydraulics also tended to be noisy. Having only one engine reduced the servicing and cost of a twin installation but meant if it failed we had no back up. Spares were cheap and easily obtained as the Kubota engine is widely used.

I have also seen a couple of Heavenly Twins with hydraulic drives powered by a Honda CX500 motorcycle engines.


Peter.
 
dancrane said:
.I'm just wondering how effective/efficient/reliable the hydraulic drive is? They're certainly compact. Not common, though.
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I have been told that you can have a bit of bother at close quarters as throwing one hydraulic motor into neutral can cause the other to run at dual speed. I expect more sophisticated systems can prevent it.

With any above-waterline engines you have to make sure the raw water pump doesn't lose prime.
 
Preachment, who supply hydraulic engine drive, told me you would expect to lose about 20% of power through the hydraulic system.

But then twin engines are also 20% less effcient than a single set up.

You pay your money.... etc,
 
Hi,

We have a Gemini 105Mc.... single engine, Selette leg, lifts up.... I believe there are more Gems made than any other Cat at over 1000... mine is #763

maybe not the best made boat in the world, but I have to say imho as a coastal cruising cat, they are hard to beat.... we get about 7kts under power

Steerable, Lifting leg, lifting centerboards, good sail plan, I think they sail very well for a 35fter... also a queen size double, very comfy :-)

It would be great to have two engines, but they would take up a lot of room under the bunks, as well as the issue of twice the servicing costs, extra wait... and lets be honest, there are quite a few yachts that seem to manage quite well with a single lump

If you get a chance, maybe you could add one to your list to look at?

Stu
 
Biggest complaint from single inboard/dual hydraulic Heavenly Twins owners is the noise, quiet loud and a bit shrill. The HT is faster than an Anderson 22 but you'll still be using the engine a fair bit.
 
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