Planing a dinghy with 3.5hp

[mikedefieslife]

Originally Posted by scareygary

Easy, Mike. Of course there are exceptions and some people travel further in dinks for some good reasons. I was simply trying to state the opinion that planing around in the dink is often not necessary. I personally long for the days when people in the PNW, at least, ROWED their hard dinks to and from their anchored or moored out boats. Seeing engines on dinks was rare, as were inflatables, actually. I recognize fully how hard inflatables can be to row. Much more peace and quiet in the 'old days' I rather long for. I DO see lots of people speeding and planing on dinks in anchorages, and it DOES make a difference to some of us. Peace out, Man....

Fair enough. I actually just took mine out today for tour of the by just out from the marina I'm wintering. I've mored up from the 2.5 (3.3hp) to a 6hp Yamaha. The difference is massive. The top speed of 15.4knts is a bit pointless, but being able to comfortably cruise along at 9-10 knts makes a difference.

When anchoring, I often row in if it's not far away. With two in the small 2,6m dinghy though it's better to motor.

I'd actually rather have an electric, but at the power I'd like it's just too damn expensive.

[botanybay]

Originally Posted by Jimmyhenry

I had a 3.4m ( I think that’s about 11feet. US of A is the only country in the world I know of that still uses feet!!) rigid bottom, aluminium, inflatable and had a 2hp Yamaha. Amazingly it would plane in flat water with just me on board sitting on the middle seat. So I think two factors are key.
1/- length
2/- rigid bottom.
Pete

I think it is partially the definition of is is (or planning in this case

My 2hp on a west marine by Avon 3.5 with high pressure floor hits hull speed at about half throttle. With two people that's about as fast as you go. It's probably 3knts.

With just me all the way forward on flat water it makes about 8 to 9 knts.

The low power guys say great its planning and cuts the time from emerald bay to two harbors (sheltered open ocean) from 30+ min to about 12 min.

The water breaks from the transom at thg he bottom and has a classic planting wake.

The high power guys claim I am exaggerating to call it planning as they zip by at 20+ knts.

I suspect different folks have a different view of what they mean by being on plane.

[botanybay]

Originally Posted by bradm85

Yea, we also use the correct spelling of realize and not realise. Even my spell check tries to correct realise.

Then there is cupper bottom paint

[scareygary]

Originally Posted by canyonbat

It is nice to have a fast dinghy when going from Marks Bay across to the Marina at Nanaimo. I want to cross that float plane landing area as quick as possible. By the way, didn’t we meet you last spring at the Dinghy Dock Pub for drinks on our way north with Bob?

Yes, that jerk was me. Just poking along, whether in the sailboat or the dink! I'm sure I found a way to tick off somebody there at the pub! BTW: I made the trip from Newcastle Island to Nanaimo just fine with my 3 hp! Likely took a couple of minutes longer. But I know what you mean about the sea plane situation. And I realize fully that some people have longer trips to make in a dink on occasion. Different strokes, so to speak, even though few people 'stroke' any more! I hope you see my point, though, about excessive speed in anchorages sometimes. It's why they outlawed PWCs in the San Juans, I think.....Great to connect with you again.... Isn't Bob just the greatest guy??

[mikedefieslife]

Originally Posted by botanybay

I suspect different folks have a different view of what they mean by being on plane.

There can't be any interpretation it's either planing or it's it displacement mode. There is nothing in between. A bit like a helicopter. It's either flying or it's not.

As I mentioned before in my short fat dinghy 2.60 x 1.60m planing begins at over 5knts, it then jumps to 7 minimum. There is nothing in-between.

[botanybay]

Originally Posted by mikedefieslife

There can't be any interpretation it's either planing or it's it displacement mode. There is nothing in between. A bit like a helicopter. It's either flying or it's not.

As I mentioned before in my short fat dinghy 2.60 x 1.60m planing begins at over 5knts, it then jumps to 7 minimum. There is nothing in-between.

You did not jump in quantum fashion from 5 to 7 knots, you went through every speed in between.

Not for very long mind you ***grin here, no offense intended***

[Group9]

We had a 25 hp on our 11 foot Boston Whaler one cruise. And, although we puttered everywhere, 99 per cent of the time, and it was heavy as all get ou to mount and dismount, it was nice to be able do 30 mph when we needed to.

But, we had a 3.5 hp the next time!

[chook]

I also love our Torqeedo 1003, have just reviewed it as have been asked by so many people, always getting stopped, hopefully this helps, good luck

https://www.youtube.com/watch?v=By48s6P8K1A

[ShipOfFools]

that electric motor is expensive and doesnt last long at low speeds

[bobnlesley]

Originally Posted by lancelot9898

...10 ft inflatable floor dinghy...3.5 hp outboard...is there anyone out there that can get the boat on plane with such a small outboard...

Yes, but he must be about 90 years old now: There was a guy who used to tune the majority of the privately entered Yamaha 2-stroke motorcycle race-bike engines in the UK back in the 1980's; I suspect he might've been able to squeeze enough power out of the motor to get you planing, but otherwise: No.
We have a 8' Walker Bay rib which one-up our 3.3 hp outboards can get 'onto the plane' though we rarely do so as the noise's with a wide-open throttle's unbearable. Surprisingly (or perhaps not?) Our 20 year old Mercury - which only actually claims 3.3hp - pushes the dink faster/more easily than the 'identical' two year-old 3.5hp Nissan version of the motor.

[Rdubs]

Hopefully this isn't a thread hijack since the question is somewhat related...
I have a 10' inflatable, high-pressure inflatable floor (basically the West Marine PHP-310). Fairly light, about 70 pounds. I bought a brand new 6HP Yamaha short shaft outboard, fully expecting to get up on plane with just myself on board. Unfortunately I could not. Granted, I was sitting in the back of the dinghy, but when full throttle was applied the RPM's would just race and the propeller would churn the water beneath the surface white, pretty sure it was cavitating like mad.
It seems like lots of people have gotten their inflatable dinghys to plane on even less than 6HP (I'm not a huge guy, just average). I'm thinking two things:
1) I'm not sitting far enough forward. So I'm trying to figure out what size PVC pipe I can buy from Home Depot to serve as a tiller extension.
2) I should have bought a long shaft.

Appreciate any thoughts.

[Jimmyhenry]

I think maybe check the angle of the engine on the transom.

[Hardhead]

Originally Posted by Rdubs

Hopefully this isn't a thread hijack since the question is somewhat related...
I have a 10' inflatable, high-pressure inflatable floor (basically the West Marine PHP-310). Fairly light, about 70 pounds. I bought a brand new 6HP Yamaha short shaft outboard, fully expecting to get up on plane with just myself on board. Unfortunately I could not. Granted, I was sitting in the back of the dinghy, but when full throttle was applied the RPM's would just race and the propeller would churn the water beneath the surface white, pretty sure it was cavitating like mad.
It seems like lots of people have gotten their inflatable dinghys to plane on even less than 6HP (I'm not a huge guy, just average). I'm thinking two things:
1) I'm not sitting far enough forward. So I'm trying to figure out what size PVC pipe I can buy from Home Depot to serve as a tiller extension.
2) I should have bought a long shaft.

Appreciate any thoughts.

I have a lot of experience with extremely heavy 9 foot fiberglass tri-hull dinghies with hulls saturated with water, and 4hp outboards.

I'd say try getting as much weight as possible up forward, and sitting on the middle seat if possible. If you use a gas tank, get a longer hose to keep it up forward, as well as coolers, gear, anchor, etc. You might also try buying a pair of plastic cavitation fins for the outboard - which might help a ton with the cavitation. Also, as JimmyHenry said, check the angle of the outboard, and make sure the lower unit is angled 90 degrees to the water's surface. Those are your best bets, and if that doesn't work, you might need to change one of the components. Good luck-

[Panope]

Originally Posted by Rdubs

Hopefully this isn't a thread hijack since the question is somewhat related...
I have a 10' inflatable, high-pressure inflatable floor (basically the West Marine PHP-310). Fairly light, about 70 pounds. I bought a brand new 6HP Yamaha short shaft outboard, fully expecting to get up on plane with just myself on board. Unfortunately I could not. Granted, I was sitting in the back of the dinghy, but when full throttle was applied the RPM's would just race and the propeller would churn the water beneath the surface white, pretty sure it was cavitating like mad.
It seems like lots of people have gotten their inflatable dinghys to plane on even less than 6HP (I'm not a huge guy, just average). I'm thinking two things:
1) I'm not sitting far enough forward. So I'm trying to figure out what size PVC pipe I can buy from Home Depot to serve as a tiller extension.
2) I should have bought a long shaft.

Appreciate any thoughts.

I have a very similar dinghy (10 ft., high pressure floor) and same outboard (short shaft Yamaha 6). Planes effortlessly with one person, nicely with two people, and will stagger onto a plane with three (lightweight) adults. No need for tiller extension/moving forward.

Note the motor plate that I constructed that RAISES the motor about 1 inch (I did this for more speed/effiecency).

Assuming the angle of your engine is adjusted properly (as mentioned in above posts), I would be surprised if the problem was propeller ventilation.

These engines do not use a "shear pin" to protect the drive train from damage in case of propeller strike. Instead, the propeller has a hub that is separate from the blades. A rubber(?) bushing keeps these two propeller components connected under normal operation. However, sometimes, these hubs "slip" at high power settings (I have had this happen), resulting in high engine RPM, and little thrust.

Good luck,

Steve

[waterman46]

Are you sure motor is in forward gear? Linkage may need adjusting or something else is majorly wrong with that motor or prop. If you can't see it, ask someone to check it for you.
You don't want longshaft, that is not the problem. We had a 9 hp on 8.5 ft with plywood floor and it planed with 2 adults and a child. Make tiller ext with PVC cut lengthwise about 1 ft so it expands to fit over tiller, secure with hose clamps.