Dinghy Outboard HP

[tardog]

We have a 8'10" dinghy and are about to purchase an outboard for it. I am in favor of purchasing a 4-5 HP outboard and feel it would be adequate. (I used to have a 26' sailboat that used a 4HP motor that was plenty powerful) The main reason I'm interested in the smaller motor is weight. We have a Hans Christian 38 which is not easy to get into and out of, let alone to haul heavy stuff up. So lighter is better. My boat partner feels we should have a 8-10HP motor. We'll normally have just 2 people onboard the dinghy.

On the low end of the weight spectrum, a 4HP might weigh 40lbs. On the other end, a 9.9 may weigh 90+.

If you've got practical knowledge of this, please help!

Jeff

[s/v Jedi]

For most comfort with dinghy rides: put on the recommended maximum hp. For 8-10 hp range, compare brands and buy 2-stroke, this is still easy to handle.

4 hp is fine for short rides in calm anchorages... it is very wet in Caribbean anchorages.

ciao!
Nick.

[Scott730]

Once again, I agree with Jedi. I have an 8'10" dink with an inflatable floor (wieght 70 Lbs) I have a 6 hp 4 stroke (55 Lbs) and wish I had an 8 hp.
You will have a very hard time finding a new 2 stroke in the U.S. (pollution issues).
I cruise the Bahamas and I need to use the dink often and over long distances, you will wish you had the max hp on those trips.

Scott

[tardog]

Is the reason simply for speed? Or is there some rule of physics that I'm missing?

[Sandero]

This is a tough one. My choice would be a RIB with LARGE tubes and an engine which is manageable without a crane. I've had everything from 3 - 9hp 2 and 4 stroke wood floor inflatables and RIBs.

I don't see the utility of the larger motors for MOST cruisers when you can get there with a smaller engine. AND planing through an anchorage is bad form anyway.

If you anchor way out a lot of the time in choppy water you need a dry fast boat. But more than fast you need DRY.

[David M]

It really depends on two things. What is the maximum allowable horsepower on the dinghy's capacity plate? Do you want the boat to be able to plane? If you don't care about planing then a 2.5 or a 4 horsepower would work fine. If you want to plane with a couple people aboard, then you want a minimum of a 9.9.

Yamaha Four Stroke Portable Specifications

A dinghy that can plane can get you to further places for some exploring around. The downside is of course the greater expense and greater weight.

[thinwater]

Originally Posted by David M

It really depends on two things. What is the maximum allowable horsepower on the dinghy's capacity plate? Do you want the boat to be able to plane? If you don't care about planing then a 2.5 or a 4 horsepower would work fine. If you want to plane with a couple people aboard, then you want a minimum of a 9.9.

Yamaha Four Stroke Portable Specifications

A dinghy that can plane can get you to further places for some exploring around. The downside is of course the greater expense and greater weight.

When it planes you ride a bit higher, and waves don't smack the front tube. It isn't just speed, it is ride.

That said, I have a 4 hp on a 9' sport boat inflatable; it will plane with one, not with two, and the ride is drier on-plane. But for putting around a calm anchorage where I really have to stay off-plane and go slow, the 4 hp is nice and light. I am happy with it. I have a catamaran and the space between the transoms JUST fits what I have in there.

One solution is to put a real pulley set on the transom. I changed the original 3x set-up on mine to a 6x bullet block with cleat set (bow and stern) and I STRONGLY recommend it. It is very nice, allowing easy controlled lifting, and easy stopping at any point. With a good purchase like that, getting a 9.9hp up should be easy enough. My reason was a bad back.

[Soft Air]

When I bought my boat it came with a brand new Yamaha 15 HP and a Caribe Dink, I have the feeling that my PO was just excessive, I am now having a hard time hoisting that big engine back to the mother ship, I was wondering besides spending money what was this guy thinking about? I would have been a happier camper if I would have gotten a 9 HP and a smaller Dink, my dink is capable of carrying 5 persons but I am a single handler.

Money does not always reflect smart brains I guess haha

[Sandero]

A 9HP is probably over or close to 100# and that is not easy to lift off and dink and plop on a rail bracket. I have to use a Garhauer demountable lifting davit which is a very nice piece of gear. It does allow a single hander to lift up a heavy dink as I do it too often now... it's not much of a hassle.

Planing IS drier, but larger tubes make a drier boat too. You can also over trim so your bow is very high and that is dry too.

I don't care to plane through chop any way.

[Soft Air]

djef I check this lifting davit by Garhauer in California and it looks real good for a single handler married to a heavy outoboard, you can throw it overboard or get it back home easily...not too expensive.

[Highlander40]

OK , the lightest weight / highest HP is a Yamaha 8 HP 2 stroke.
This OB will be fazed out but I bought one last year. Will easily plane 2 people.
Still light enough to lift by hand. I think 60 lb.
6 hp and lower and you are forever in the land of 4 kts.

10 lbs more and you go 12 to 15 kts, do the math.

Carl

[Sandero]

JC,

This is a first class piece of gear and well worth the cost. I can't recommend it highly enough and it comes apart in 15 seconds and is easy to stow and you can swing it around to lift a battery into the cockpit. I'm sorry I didn't have one when I had a 64# 6hp which was a PITA to get on board.

This lift is to me analogous to a windlass. You can anchor without one, but with a good one it makes setting and upping the anchor almost a non issue - no stress. When some might be tempted to tow their dink with the motor on for 10 or 20 miles, with this you wouldn't even consider it.

But this is not going to get me into anything more than the 8-9.9 HP which planes if we want.

[Soft Air]

defjef thanks for your information about this gear, I notice they offer two types a collapsible one and a non collapsible one, I need to see what is the weight of this Yamaha 15 and make sure it will work with it. I also notice the two pieces of gear have different arms.

I am seriously considering in getting one of this as I will be soon in a third world country where people may be tempted to grab the engine, different thing if I can easily bring it back to the mother ship and secure it, they will think twice before trying to get it, so yes if it works as you say it is worth the price as this engine is brand new and quite expensive.

Thanks for the absolutely great info you are giving me sir

[Sandero]

JC,

I think I have the short arm. I suppose the consideration would be the beam of your dink and the config of the stern. But the block and tackle will reach. The only issue is when lifting you want it to go straight up which is easier as the OB screw locks can snag on the motor mount for an instant.

I will raise the motor by myself from IN the dink with one hand on the line and the other sort of guiding the motor free of the motor mount. Once clear your good to go. Since it has a cleat you can then go into the cockpit and hoist from there, again one hand for the motor to guide it onto the rail mount. It's really very simple. My motor is about 100# and I have no problem with it. You do need a good lifting harness for your motor, which I leave on all the time.

If you don't want someone to cut your painter and make off with your dink, hoist it out of the water with the main halyard and it will be out of the reach of the typical thugs who might consider quietly cutting the painter.

[Soft Air]

Thanks djef very nice info, I will talk to this guys and see which of the two they would recommend I will definitely get one to protect this expensive engine. I was also thinking that once the engine is back to the boat the dink will still be at risk so it is a good idea as a second stage to hoist it out with the mizzen halyard, after that I think they will think twice before attempting to grab any of the two don't you think?

I will add some secure cables and locks for both to make it even more secure. I don't want to go paranoic but I am so broke that I cannot afford to loose my dink that connects me to the rat race world when I need supplies from there haha

Dink robbers should be given death sentence or at least to share jail with Mudoff