SIB Not planing

Wazzajnr · 29 April 2015, 22:07

Hi to everyone, New here but hope to be on here much more often.

Just bought one of these,
Inflatable Dinghy River Boat Tender w/ Aluminium Paddles & Flooring Family Size for 4 Adults and 1 Child: Amazon.co.uk: Sports & Outdoors

And I must say, it seems a really well made bit of kit. As some of the reviewers mentioned, the floor plates doo have some sharp edges but 10 minutes with a fine file and all sorted.

Reasonably easy to assemble although the side pieces on the floor can be a bit of a pig to clip into place.

Also, the supplied pump seems to keep the valves open slightly so when you're inflating it, there is air constantly escaping which means you have to pump like crazy then quickly remove the adaptor before too much air escapes.

Apart from that it seems pretty good. However, on testing it this week with a brand new Chinese 6hp 2str, it wouldn't get on plane with myself and a teenager in it.

So, can anyone comment on whether I should expect this to plane with a 6hp or not and also, is the valve/pump not right??

I haven't tried it one up as the weather was poor later in the week.
I've tried shifting weight and still couldn't get it on plane.

Has anyone used Doel fins (or similar) and did you have any luck.

Don't really want to go to bigger engine as the weight of this one is about as much as is comfortable. I could carry more but it would make it become a grind rather than a means to an end!!!

Thanks in anticipation.

Paul

Landlockedpirate · 29 April 2015, 22:26

Thats a big sib to get on the plane with a 6hp motor.

Doel fins are marmite, love em or hate em, but if its just on the edge of planing they may work.

Lots of people will be along shortly to tell you their boat planes with a 3hp or similar, but my feeling is you need more power. 10hp should do it, but since they are similar price and weight, 15hp (Mariner, Mercury, Yamaha etc) would be best.

If you are going to stick with the 6hp. just enjoy the boat as it is, lots of fun still to be had at 6kts.

Wazzajnr · 29 April 2015, 22:32

Yeah, there was a reviewer on there saying that theirs planed with 4hp and I remember a mate of mine 20yrs ago who had an inflateable that planed with the old evinrude 4hp twin cylinder. (I had the same motor on my little cathederal hull boat but it wouldn't plane except at full throttle with me hanging over the front and steering by leaning side to side!!!)
One of the reasons I bought it was because I wanted to get up on plane for a bit of fun.

I'll still enjoy pottering along but would like a bit of a thrash now and then, I guess I though 6hp would just about cut it based on a memory from 20yrs ago!!

Landlockedpirate · 29 April 2015, 22:41

As a kid I could plane a ZED 31 (Zodiac 310) with a 4hp, and a few years ago I got a Honwave T27 to plane with the same engine -by hanging over the bow with a loooooong tiller extension, but it wasnt very practical (and fell off the plane with the slightest headwind, wave or weight shift).

Your best option for power V weight is a used Tohatsu 9.8, they are only 26kg and should easily get your boat on the plane with 2 up.

Festinghouse · 29 April 2015, 22:42

hi, where are you, and where do you take the boat? my 3.2 planes ok with an 8hp on the back though i did have to put a smaller prop on it - may be worth trying as its like dropping a gear in your car to gain more acceleration

Wazzajnr · 29 April 2015, 22:49

Landlocked, I'm getting a bit too old too lean over the bow and steer by leaning side to side these days!!!

Festinghouse, I've just been up to Keswick for a few days as the caravan site is directly onto the water. I'd like to find somewhere closer to home to use it though really.
I live in Chorley Lancs and on boatlaunch, there didn't seem to be anyhere close that took my eye.
We're only 200yds from the canal but it seems that a licence is not cheap to use on the canal so that's on a backburner for now.

Wazzajnr · 29 April 2015, 22:50

By the way, a smaller prop may not be an option as this is some cheap Chinese copy engine so not sure what would fit!!

Festinghouse · 29 April 2015, 22:57

i would suggest knott end as the best local place to lauch. i too have thought about the canal as botany is just down the road from me but never had time to sort anything out over winter. best bet would be to take your prop to bill highams and see what they say

Wazzajnr · 29 April 2015, 23:02

We must be neighbours!!!

Knott end sounds like an OK place but I've avoided the sea for now as I just want to convince myself of the reliability of this Chinese engine first. I'ts easy to row to the shore at derwentwater but easy to get dragged to sea with no power elsewhere!!!

So where is Bill Highams then? Might have a look/see.

Festinghouse · 29 April 2015, 23:17

its not too far from us - ten mins off the m61 and they literally have a room full of props all different sizes. if you want then fetch your boat down to holyhead and i will be your safety cover in case of breakdown

Wazzajnr · 29 April 2015, 23:20

Thanks for the offer. Might just do that if I can get it running a bit better. 4-5 knots isn't much fun but I'm sure it should go better than that.
Going to have a fiddle with the engine as they're probably not to well set up from the factory!
I'll keep you posted!

Festinghouse · 29 April 2015, 23:31

ok cool, send me a pm if you want me to take a look though cant promise i can do much!

Wazzajnr · 29 April 2015, 23:42

Ok, will see what I can do in a couple of weeks. I'm away until then. The prop does sound like a possibility though. The engine revs proportionally to the throttle till about just over half then add you wind it further, the induction roar goes up but with very little increase in revs suggesting that it's not getting up into its power band. I know from my 2 stroke motocross days that 2 stroke engines have a fairly narrow power band.
I need to see if I can get my handheld tacho on the crankshaft whilst it's running and see what rpm it's doing.
It sounds a bit like when I get my chain stuck on the chainsaw.
Food for thought indeed. Thanks for the suggestion. I'll be in touch when I get back from my European sales tour!

Fenlander · 30 April 2015, 00:03

That bogged sound is what you get when an outboard can't make it on the plane. You are right on the crossover HP at 6 for an adult + teen. Weight is crucial with minimal power. There is a big difference in that situation between you being lightish at say 11st plus 7st teen girl... or you being 16st with a rugby playing lad of 14st!!

Would be interesting to try it one up with the lightest of the two of you.

Max... · 30 April 2015, 08:15

As Fenlander says, weight is key - get the lad to sit at the water edge while you try it alone.

The smaller the power of the engine the smaller the weight (that makes the) difference between planing and not planning!

And a tiny tach is only £10 or so on eBay and will tell you the revs very easily.

Wazzajnr · 30 April 2015, 08:21

Ah right, I have a hand held tacho but it would mean taking the cowl off the starter. If it's only a tenner or so for a tiny tach, I'll buy one.
I think if I'm going to play with props etc, it's necessary to know the rpm of the engine to see what difference things make.

Dave Cowell · 30 April 2015, 08:22

We are based in Chorley, you are welcome to bring the boat to us to check out the valves and pump

Wazzajnr · 30 April 2015, 08:28

Thanks Dave, can you send me a PM with your details please? It will be after I get back from my sales trip but would be good to have someone local who can help.
Thinking of buying a good electric pump anyway so hopefully that will come with an adapter that works well.

Fenlander · 30 April 2015, 09:47

I wonder what make your Chinese outboard is? Do you trust it is making its stated output? If it's nearer 4hp in reality then you'll never plane unless one up with a superlight person.

You didn't respond to my weight comments a few posts above... not meant to be insulting but there's lots of experience on here and if you gave an idea of total weigh of you + passenger then we'd have a better idea of the likelihood you'll ever plane it.

Wazzajnr · 30 April 2015, 10:12

Fenlander, The outboard is a Hyfong and at the rpm I'm achieving, it's almost certainly not making 6hp which is why I thought the smaller prop might help. I'm guessing at the moment but I would say I'm not much above 3000rpm at WOT and the engine is rated at max rpm of 6000. A variable pitch prop would be a wonderful thing!!!!

Sorry I didn't respond to the weight, I thought you were just saying "weight makes a difference" I didn't think you were asking for info. No problem though.
The lad is about same height as me but hasn't filled out so I would guess he is about 80kg and I'm around 90kg.
When I had a short run with the missus (75kg) leaning forwards with her up front seemed to increase rpm and speed ever so slightly but it still wasn't planning.

I'm fairly sure one up, it would go OK and I think that the engine just isn't getting into it's power band so to speak.

I'm assuming that a lower pitch prop would allow the engine to rev higher but would reduce the overall top speed once on the plane, am I correct??