Thought on Yamaha8hp (Long) for dinghy and 24ft yacht?

[Guest]

Hi All

 

Q: What do you think on an idea to use a 8hp long shaft outboard for both inflatable and sailing boat?

 

- How difficult is it mounting 27kg motor (Yammy 2stroke) back and forth from the dinghy?

- Is long shaft outboard suitable for 2.5M inflatable?

 

I am thinking it would be quite handy for a quick trip to my boat and safe from the theives. Please share your thoughs.

 

Just one last odd question, can I push my yacht with 2hp outboard? I wouldn't mind 2~3 kts. My previous inboard wasn't that powerful either.

[Bimini Babe 0]

Sounds bloody dangerous to me...

 

I can push my 30 ft'er with a Yammy 3hp in very little wind and tide and flat water if that's any help?

 

Edit: Just rememebred - used the 2hp on the Variant when the 8Hp was in the shop - worked fine, if a bit slower.

[col j 0]

If you can lift it easy enough, i.e your a tough nuggit. then sure. The issue would be when its rolling around a bit with waves and so on.

 

As far as I know the long shaft wouldn't make too much of a difference. Might just ride a bit different than a short but not sure in which ways.

 

Regarding a 2hp pushing the big boat. What is the big boat? I think a Piedy would get the 2-3 knots easy enough but struggle if there was any breeze up.

 

I used to do a similar thing with my 8hp. Would take it off back of tender and lay it on the tender floor then pull it up with rope and fit to bracket from on the boat.

[banaari 27]

- How difficult is it mounting 27kg motor (Yammy 2stroke) back and forth from the dinghy?

Bloody awkward, I would think. I've got the exact model you're talking about; quite easily carried on land, but my aim in life is to find ways to avoid having to move it any more than necessary... there's a thread under TechTalk to that effect.

[Farrari 4]

Don't do it .... I had an 8HP Yammy on the back of my trailer sailor and there is no way I would want to shift it onto a dinghy in any sort of swell. That's assuming that you didn't kill yourself on the dinghy before you got to the boat.

 

The BBYC J24's have 3HP Mercs and they have to be towed in the wrong conditions. A 2HP wouldn't cut it on a 24ft yacht unless it was dead calm, slack tide an no chop. Murphys law says that when you really need it you won't have those conditions.

 

My 2 cents

[DrWatson 380]

Unless you're a muscle bound flexomatic, the effort and reach required to transfer a 27 kg object from the transom of a wobbly dinghy to the bracket on the transom of your yacht will be above what could be reasonably expected.

Add to that a bit of chop and 15knts coming at you it will be almost impossible to achieve without dunking the motor in the water at least three times, jambing your fingers between the bracket and the clamp, and getting your tackle caught in the lifelines as you lean over.

 

The old rule of thumb used to be 1hp per ton. Maybe they were different horses back then and most probably the engines produced more torque and swung larger props.

 

It also kind of depends on what you want the motor to achieve. It seems like you're not looking to motor back from the Barrier into the teeth of a strong SW if you're happy with 2knts.

 

If all you want is something to help manoeuvering in the marina then a relatively small outboard can be surprisingly effective and a hell of a lot cheaper and less hassle than an inboard. 4-5hp should be plenty. But if you want to motor off a lee shore, then you'll want a bit more.

[Fogg 427]

I have a yammy 5hp as my dinghy outboard do I regularly lift it on and off and it's ok but I wouldn't do 8hp as a matter of routine without a lifting system.

 

And maybe 5hp would be sufficient for your boat in light to mod conditions?

[DrWatson 380]

We had 5hp on a 727 and it was fine unless you wanted to motor into 25knts. Also light enough to lift off and on.

 

If you just want to manoeuver in still airs and flat water, you could always get an oar. Surprisingly useful, and can be used as a forward rudder to help turn quickly, fend off, and repel boarders.

[203 0]

fend off, and repel boarders.

Is that not what a boat hook is for?

[Guest]

Thanks everyone for your kind replys! It's so helpful!

 

I will now think about the other options. I got 2hp yammy for my inflatable outboard and it may be suitable just in and out of the mooring. I have SS24 falcon. Its displacement 4620lb = 2.1 ton. It just cuts it by the old rule, referring to DrWatson. I might give it a go if I don't get the bigger motor.

[Brendon 0]

I'm sure I read somewhere that the old rule was 5HP per Ton, which in my experience is about right. A lot of small yachts and Trailer sailers seem to carry outboards far in excess of their needs.

 

I certainly wouldn't consider transferring an 8Hp except on land.

 

Try the 2 Hp on the boat on a calm day and you will probably be surprised at the speed you can get up to, it will just take a while to get up to speed. But if you ever have to beat into contrary conditions you are going to want more HP.

[DrWatson 380]

I think it depends on which "old rule" you go for. Some state as little as 0.5 hp per ton for ocean cruising and 1hp per ton for coastal. Others insist on as much power as possible.

 

Pardy and Hiscock suggest 1 hp (but Pardy has no motor at all).

 

I'd go for a 5 if I were you but try the 2 first.

 

R

[johnmac 3]

I used outboards on my keelers for many years.

 

What I found is that a higher horsepower outboard isn't automatically any better than a smaller one in pushing a yacht into a strong wind if there's a sea running. In those conditions half the time the propeller is out of the water due to the yacht's pitching. I found the best solution for outboard powered yachts in a strong wind and big seas is having good heavy weather jibs & a well sorted mainsail reefing system. In those conditions, forget motoring and use the sails. Keep the engine for calms and picking up the mooring or in the marina.

 

In my experience most yacht outboards have the wrong propeller with excessive pitch. This bogs the engine down and prevents it getting into its power band. Most outboard dealers have no idea how to correctly specify pitch for yachts, they just guess at it. The propeller MUST allow the outboard to reach its max rated rev's (usually between 4500 and 5300 rpm), which will deliver the most thrust. The only way to do that properly is to test the engine/propeller combination with a portable rev counter on the actual yacht itself. If the engine can't reach it max rev's, go down in propeller pitch until it does. It may take two or three goes to get it right, but it's time well spent. Many yachts are running around with props with far too much pitch, which will kill their engines real early - two strokes love to rev.

 

Overall I found having the smallest horsepower outboard, correctly pitched, is a far better option overall than an engine too heavy to lift. Personally, a 5hp two stroke Yamaha (21 kgs) is my comfortable max limit - the 8hp (27kg) is far too heavy for me to easily lift off the back of a yacht. I used a Tohatsu 3.5hp (12kg), and with the correct prop that easily pushes a 2 ton Folkboat to hull speed. IMO, two hp per ton (with correctly pitched prop) is ample.

 

But you must have good sails for strong winds. We found numerous times by tacking up Auckland Harbour into strong SW winds (25 to 45 knots) we'd be far quicker under sail to Westhaven from North Head than similar length yachts motoring. We'd be doing 6 knots easily and comfortably, they'd be down to 2/3 knots, pitching like hell, props waving in the wind and the engine screaming its head off.

[khayyam 77]

we have a 9.8 longshaft on a dropdown bracket for the 727. it's not light, and wouldn't dream of putting it on the dinghy. but in the odd situation where you find you want to motor into the tide and a stiff breeze, it's good to have the reserve power. i would say that longshaft is pretty important -- doesn't matter how much power you have if you can't keep the prop in the water in a nasty sea.

 

that said, i just find it unpleasant motoring and we almost always sail. that's what the little sails and reef points are for!

[B00B00 310]

I used to swap a 15hp yammy between my old 1/4 toner and the dingy. It wasn't easy and not something I did every day but was really handy if you wanted to go across Bon accord or Fitzroy harbor to get grocery's.

 

On the SR26s we take the outboards off when racing, they range from 5hp to 15hp, its not easy but manageable. I made a padded bag for the outboard with handles so you just dropped it into the bag and passed it down stairs.

[Marshy 30]

Ive got a Mercury 15hp (Rebranded tohatsu 18hp) weighs 37kg and i can lift it off the back of the boat, it aint light but we take it off for racing. But it depends on the transom layout and where the bracket is. We are open transomed so access straight above the outboard is easy as and makes it much nicer.

[Bimini Babe 0]

I made a padded bag for the outboard with handles so you just dropped it into the bag and passed it down stairs.

Sounds like a good idea... Having trouble visualising it though. At the risk of drifting... could you explain further?

[S+S24 0]

G'day, I have an S&S 24 standard version with a 15hp Mariner longshaft on it. Absolutely brilliant but no way would I transfer it to a dinghy. Permanently attached via various anti lowlife systems. I used to race in the eighties on one with an Evinrude 9.9 and we used to move it inside, now older and lazyier so 15hp stays on back. Will be doing SSANZ next year and will change to 5hp Yamy to reduce weight. Summary ... 15 or 8hp for cruising or need to get somewhere on time, 5hp do job for racing and don't need to be back at work on time!

[Guest]

Can you please recommend me ss24 bracket option? What is lowlife system? I am looking different bracket brands. Any commend would be appreciated. Thanks

[col j 0]

lowlife? i believe hes talking about the type of people that set about making a profit from other peoples hard work. i.e stealing sh*t

 

anti lowlife would be chains/padlocks/100,000 volts passing through it that the would be light fingered git doesn't know about until he grabs the thing and he is shot 100m away, hand still attached to outboard, attached to the boat