Planing a dinghy with 3.5hp

[MLOI]

Originally Posted by canyonbat

We have a 9ft inflatable floor Achilles with a 6hp Honda and it struggles with the two of us to get on plane. Once it does it is scary as can be. Kind of reminds me of one of those round saucer sleds. I may not be pumping the floor firm enough.

We have the 10ft Achilles. With a 9.8 HP 2 stroke stuck on the back it planes 4 of us.
With just me and the boy it is a lot of fun
I do feel the occasional twinge of guilt for using a 2 stroke. But then we go really fast and it goes away.

Mike

[hamburking]

I had an Avon Rover 3.1 (10 feet) with inflatable floor and a yamaha 4hp. My teenage daughter could easily plane with that. I could not. I'm twice her weight.

[watevaworx]

I have a 3.1 m Highfield with a 3.5 hp Merc and it plans great with just one person and ok with 2 as long as they are not to heavy . I had a Proline 3.1 m
high pressure inflatable floor dinghy before and it still planned ok .

[Montanan]

Originally Posted by ShipOfFools

Awesome stuff! do you think these would work on an inflatable catamaran?

Does the inflatable catamaran have a transom to connect and support the Lifters, if so then they should add what is the the equivalence of longer LWL. Seemingly, one would need to balance the weight fore and aft to adjust for the extra lift in the rear derived from the Lifters. I would ask the manufacturer for specific guidance, I'd be at best guessing. Perhaps purchase the kit with the their specific right to return if it does not improve performance, such transaction being a trade off of risk and a means for the company to find out if their product has alternate use potentials. I am typically game to work with select prospective customers to utilize my company's products or technologies for fields of use outside of what our perceived usage has been. One never knows unless you try!

A video from the same company showing a sail kit for an inflatable dinghy making for boat fly. I don't see Lifters on this sail rigged inflatable dinghy which also has a small outboard motor mounted presumably for when their is no wind to sail the vessel.

https://www.youtube.com/watch?v=clH_Uo9LpLw

[jkindredpdx]

I have a 10' inflatable with a Minn Kota Riptide 55 lbs thrust powered by 2 12 volt lawn mower batteries. The motor weighs about 20 lbs. The batteries are about 5 lbs each. No Planing, but it scoots along ok with me, my 52 lb dog, a large ice chest, and fishing gear... and it is very quiet and zero maintenance.

The inflatable is packed in a compact bag on deck for the winter. The motor hangs easily from the aft rail...

[mikedefieslife]

Originally Posted by jkindredpdx

I have a 10' inflatable with a Minn Kota Riptide 55 lbs thrust powered by 2 12 volt lawn mower batteries. The motor weighs about 20 lbs. The batteries are about 5 lbs each. No Planing, but it scoots along ok with me, my 52 lb dog, a large ice chest, and fishing gear... and it is very quiet and zero maintenance.

The inflatable is packed in a compact bag on deck for the winter. The motor hangs easily from the aft rail...

The OP wants to plane though.

My boat came with an 80 lbs thrust electric engine. It was one of the first things I got rid of. It ran off a 20kg FLA battery, so made no sense at all. It's equivalent of about 1hp and combined with a battery is more weight then a even a large 2 stroke.

[VBsail]

I prefer getting a 6 hp motor, but the weight is close to 60 lbs and I don't think I can handle that without a crane. There are some 2 stroke outboards on sale on Amazon which weigh in at 40 pounds, but unsure of the quality. Didn't even know that it was possible to buy here in the US. Any comments about these outboards made in China?

There is a decent amount of videos of the 40lb Hangkai 6hp 2 strokes on youtube. They are an almost exact clone of a Tohatsu M5B. (also sold as mercury 5m) Cross reference of hangkai/tohatsu shows the same lower units and props, carbs, ignitions, and most other parts. The hangkai carbs, props, ignitions & replacement parts are sold on amazon/ebay inexpensively or the tohatsu parts can be used from what I have read. Initially the clones used a tohatsu upper end and lower end from a yamaha 4, now its just a complete tohatsu clone.

Most of the youtube/amazon/reviews of people who actually buy one seem to be happy, everyone who hasn't has doom and gloom horror stories to stay away.

The reviews seem to be drastically different for the 3.6hp version. I helped my neighbor set up his chinese 3.6 to start with a cordless drill since he has neck problems. It works, but I wouldn't personally buy one of the 3.5/3.6.

BTW, boatstogo sells saturn NC290 catamarans for $500 shipped.

https://www.boatstogo.com/inflatable...aran-nc290.asp

[waterman46]

If you really want the dinghy to plane and be useful to carry two people, you will probably want 8 hp. It isn't a big deal to use a 4 part tackle connected to your boom.

I don't know it's weight precisely, but have used an 8 hp Evinrude 2 stroke that I could lower and raise from dinghy to deck hand over hand, by tying it to a big fat rope. I'm just an average strength guy. I'm pretty sure it must have been a bit less than 60 lb. That motor would plane an 8' Zodiac with inserted plywood floor boards and an inflatable keel, with me, the gas, wife and small child.

[waterman46]

Originally Posted by mikedefieslife

I'm not sure why people think it's so difficult to plane a small dinghy with a 2.5/3.5 motor.

My Mercury and my Marinier 2.5 (with restriction removed to make it 3.5) would plane my 2.6m 33kg inflatable dinghy up to 8knts in perfect conditions, more like 7knts in others. It would not plane with 2 people though.

There is a British magazine test of dinghies less than 3m and IIRC nearly all of them would plane with the 2.5hp motor

https://www.mby.com/gear/the-ultimate-tender-test-26057

At 7 knots are you actually planing? Anyway I think the goal of the OP was to go a bit faster than 7 or 8 knots. I would think 10 as a minimum.

[sailhand]

My dinghy planes easily with a 3hp and two people, however it is 3.5 m long and 1.8 metres wide. It also rows really well. A friend with a 2.3hp air cooled honda on a small 8ft pram raced me over three miles, he motored and i rowed. I beat him by about 200 metres and it would have been a lot more if i was fitter, i kept slowing down for a rest and even stopped at one stage. As soon as he would catch up i would start rowing again. He was hanging right over the bow on the pram at one stage trying to go quicker but to no avail. It was quite surprising as it doesnt seem that fast, i guess dinghys with a short waterline length and rocker are always going to be slow. I have always rowed faster than inflatables with small outboards. They seem to push up a large bow wave like a car fording deep water and this makes them incredibly slow. Once you have enough power to plane them it is a very different story though. Their light weight and flat bottom, in the case of airdecks, makes them really skoot along. There are airdeck inflatables that are quite long and skinny almost like a canoe. These plane with much lower horsepower due to their longer narrow hulls. If you dont like rowing they also paddle reasonably well with a double ended kayak paddle as they are narrow. If you are restricted to lightweight inflatables then these long skinny air decks might be just the ticket.

https://m.youtube.com/watch?v=4sRFHqErHnI

[mikedefieslife]

Originally Posted by waterman46

At 7 knots are you actually planing? Anyway I think the goal of the OP was to go a bit faster than 7 or 8 knots. I would think 10 as a minimum.

Yep, once 5.5 or so the dinghy rises up and begins to plane. There is kind of nothing in between. It's 7knts plus or less than 5.5knts in displacement mode.

[VBsail]

I like those long skinny kboats. If I didn't need something under 10' to fit on my bow I would have really considered one.

I took a video running up a creek off the ICW yesterday while waiting out fog. 40lb 6hp 2 stroke and 9' nanocat. 16 top speed, steady stable 14 at 3/4 throttle & 200lbs on board.

https://www.youtube.com/watch?v=z7I0...ature=youtu.be

[mikedefieslife]

Originally Posted by VBsail

I like those long skinny kboats. If I didn't need something under 10' to fit on my bow I would have really considered one.

I took a video running up a creek off the ICW yesterday while waiting out fog. 40lb 6hp 2 stroke and 9' nanocat. 16 top speed, steady stable 14 at 3/4 throttle & 200lbs on board.

Ah, so you're the one that bought a Hangkia then. How is it?

[Terra Nova]

Originally Posted by lancelot9898

I plan on getting a 10 ft inflatable floor dinghy and because of weight restrictions on the outboard, using only a 3.5 hp. Is there anyone out there that can get the boat on plane with such a small outboard?...

I just listed my Avon roll-up which will easily plane with a 3.5hp outboard. Plenty of boats will do this.

[MrWesson]

My 9.4 west marine plastic dinghy(sun dolphin) will plane with a 3.5 tohatsu pretty easily.. Just can't be sitting towards the back. I weigh around 215.

Barely use it and so far i'm the one one who's been in it.