engine for inflatable

anthony · 18 October 2005, 14:46

I have just brought a bombard aerotec 380 and the boats weight is 43kgs.In the manual it recommends a 15hp engine with a maximum of 25hp.Is it necessary to go to maxium hp considering a 25hp(2 stroke) weights 50kgs and a 15hp(2 stroke) weights 36kgs and would i get full use of of the 25hp engine in light boat.I am looking to use the boat with 1 or 2 adults or 2 adults 2 children and also be able to tow a inflatable ring for the children and a top speed of around 20mph.Would i get this from a 15hp engine.

simmons0 · 18 October 2005, 15:18

Just to throw something else into the equation, i've wakeboarded behind a 4m inflatable with a 25hp two stroke.

I don't think that would be possible with anything less than a 25hp engine.

Hugh Jardon · 18 October 2005, 19:18

Quote:

Originally Posted by anthony

I have just brought a bombard aerotec 380 and the boats weight is 43kgs.In the manual it recommends a 15hp engine with a maximum of 25hp.Is it necessary to go to maxium hp considering a 25hp(2 stroke) weights 50kgs and a 15hp(2 stroke) weights 36kgs and would i get full use of of the 25hp engine in light boat.I am looking to use the boat with 1 or 2 adults or 2 adults 2 children and also be able to tow a inflatable ring for the children and a top speed of around 20mph.Would i get this from a 15hp engine.

not sure if you would carry the boat and engine in your car or trailer it, if you can go for the 25hp if you can lift one etc

i have a 3.4 with a 15 and is fab, the 3.8 with a 25 would be superb, dont get a 15 go 25

the major consideration is if you pack it up and have to lift the engine into the car then make sure you can lift a 25, and walk with it etc

codprawn · 18 October 2005, 19:40

A great compromise would be the Tohatsu 18hp - same weight as the 15hp!!!

BTW just read all small 2 stroke outboards will be banned from sale in the EU by 2007!!!

hard1 · 18 October 2005, 20:05

That's if they don't crack the emissions first. Don't bet on it....Necessity is the mother of invention.

Poly · 18 October 2005, 20:07

...I have a slightly bigger boat that weighs 3x as much and was bought for similar purposes. It carried the manufacturers recommendation of 20 HP. She goes like stink

The max is a 30 HP - people who have far more experience than me have suggested that anything bigger than my 20 HP would really be a waste of money. There are plenty of people here who will tell you that bigger is better - but remember its an inflatable boat - do you really need want that extra few knots, or need to get on the plane that much quicker.

I'm guessing that like me you went for a relatively inexpensive boat because you didn't have buckets of cash to throw at it - so I would suggest you might want to save money on the engine too - and Codders suggestion of the 18HP tohatsu is probably a good one. Picking the right prop will be important especially for towing.

Oh - and by the way my 20HP Yamaha engine - weighs about 50 kg if I remember correctly and I can only JUST lift it on to the transom on my own. I doubt I could lift it off the transom up on to a jetty. I'm not Geoff Capes but I'm also not totally weak. My wife who regularly moves 25 L drums around on a chemical plant can't lift it at all.

HTH...

Neil

codprawn · 18 October 2005, 20:08

Quote:

Originally Posted by hard1

That's if they don't crack the emissions first. Don't bet on it....Necessity is the mother of invention.

Most of the makers won't bother - they will just use 4 strokes instead - with bigger 2 strokes it is not a problem as they use direct injection and computer control but just too expensive for smaller engines - not many injected engines on tenders!!!

Apparently commercial craft and rescue boats will be exempt though - RNLI probably had a say in the matter!!!

Poly · 18 October 2005, 20:11

Quote:

Originally Posted by codprawn

BTW just read all small 2 stroke outboards will be banned from sale in the EU by 2007!!!

My outboard supplier states:

EU 2006 Emissions Standards Label represents conformity to the EU emissions standards proposed by the Commission of the European Communities on 12th October 2000. IT IS THE ONLY EMISSION STANDARD THAT AFFECTS UK AND EU ENGINES. All other emission standards are irrelevant for the UK and the rest of the EU (for example EPA 2006, CARB 2004 /2008). The EU2006 standards will only affect the SUPPLY of NEW outboards for ‘RECREATIONAL’ use. By ‘recreational’, the regulators exclude engines for commercial registered vessels and racing engines. This text only is only with regard to recreational engines. ALL engines sold PRIOR to the full implementation of the standards on the dates shown below, may continue to be used. Effectively, after 31st December 2006, any NEW spark ignition two stroke outboard motor which does not meet the EU 2006 standards, (basically conventional carburettor / E.F.I. 2-strokes) will cease to be imported / manufactured into the UK and the rest of the EU. However, any engines held in stock by EU importers or dealers, which have been tax paid, are exempt as though they had been sold prior to the regulations. Equally, only spark ignition four stroke and compression ignition (diesel) outboards, which meet the regulations, may be sold from 31st December 2005, with the same exemption about stock units. It should be noted that the spark ignition four stroke and compression ignition engines are required to meet the regulations a year earlier than spark ignition 2-strokes. (For more details see "Emissions: The Truth") Unlike the EPA and CARB standards, the EU 2006 standard covers three constituents of exhaust emissions, and noise levels. The exhaust emissions included are nitrous oxide and hydrocarbons (as included in EPA & CARB standards) plus carbon monoxide. Consequently the EU 2006 standard is the most difficult to attain compared with EPA and CARB. Unlike the US standards that allow a percentage of ‘dirty’ engines to be sold, the EU 2006 standard will affect EVERY NEW engine sold in the EU. The EU 2006 standard is also the only standard that also covers noise levels for outboards. It should be noted that the EU2006 standard also affects inboard engines in a similar manner to outboards. e.&.o.e.

codprawn · 18 October 2005, 20:18

I have a Quicksilver 310 with a suzuki 15hp 4 stroke - although it is a great engine it is quite heavy at 45kg - I am very pleased with it's performance - even heavily laden.

I would have thought your boat would be ideal with an 18hp light 2 stroke. 2 strokes are better for smaller boats - and much easier to transport!!!

One thing that makes life SO much easier - get a set of launching wheels - the decent ones with big pump up tyres and stainless legs - make lif so much easier. they just swing up out of the way when you aren't using them.

http://www.rib.net/forum/showthread.php?t=11172

And you will see what I am on about.

anthony · 19 October 2005, 14:02

Yes i will be carrying the boat and engine in the car.So would a 2 stroke be the best option?I have narrowed down my choice to:

15hp 2 stroke tohatsu/yamaha (37kg)

15hp 4 stroke suzuki (45kg)

18hp 2 stroke tohatsu (37kg)

20hp 4 stroke honda (46kg)

25hp 2 stroke tohatsu/yamaha (48kg)

does anyone have any comments about this engines.

yes i do have some launch wheels for the boat.

ashbypower · 19 October 2005, 14:15

My Instict would say 2 Stroke because of weight, I also believe that some (if not all) 4 Strokes are Finicky about how they are laid down. Perhaps others may have experience of this. All IMHO of course.

Enjoy your new boat which ever way you power it,

Brian

codprawn · 19 October 2005, 15:48

Quote:

Originally Posted by anthony

Yes i will be carrying the boat and engine in the car.So would a 2 stroke be the best option?I have narrowed down my choice to:

15hp 2 stroke tohatsu/yamaha (37kg)

15hp 4 stroke suzuki (45kg)

18hp 2 stroke tohatsu (37kg)

20hp 4 stroke honda (46kg)

25hp 2 stroke tohatsu/yamaha (48kg)

does anyone have any comments about this engines.

yes i do have some launch wheels for the boat.

I am very pleased with the Suzuki 15hp 4 stroke but for the same weight you could go for a 25hp 2 stroke!!!

As you boat is quite a bit heavier than mine maybe you should go for the 25hp - you don't HAVE to run it flat out - in fact you may get better economy with a bigger engine as you don't have to push it so hard.

All depends how much lugging around of the engine you are going to do - with my 4 stroke it is really a 2 man job to lift it out of the boot and onto the transom.

As regards being layed down it isn't really a problem as there are 2 lugs on the side which needs to face down. As long as you remember no probs. I can't help but think it can't do the engine much good though. My Suzuki runs fine but when you first start it there is a cloud of white smoke for a few seconds.

To sum up - if weight not a prob get a 2 stroke 25hp - if it is a bit much get the 18hp. To be honest with these SIBs you can't go flat out very often anyway unless the Sea is like a mirror - just gets too bouncy!!!

John Kennett · 19 October 2005, 16:04

Quote:

Originally Posted by codprawn

To sum up - if weight not a prob get a 2 stroke 25hp - if it is a bit much get the 18hp. To be honest with these SIBs you can't go flat out very often anyway unless the Sea is like a mirror - just gets too bouncy!!!

I'd go along with that. I'd recommed going to a dealer and doing a couple of laps of the showroom carrying each motor to see how you get on!

I had a Zodic Mk1 GT (3.5m) with a 15hp 2 stroke, and it went like a rocket with two people on board and could just about plane four-up. I wouldn't want to carry the engine very far, but it was easily manageable most of the time.

I also had a 4m Avon inflatable with a 25hp outboard which was pretty quick even with four people. The motor was that much heavier though and was a real struggle to move any distance. It was very exciting when the (badly bodged by previous owner) floor came apart on the Thames in the middle of London!

John

simmons0 · 19 October 2005, 17:42

Have a look at ex-RNLI Mariner 25hp 2-strokes - Not many hours on them, near perfect condition and come out pretty cheap.

Not sure where you would get one, but a mate did and his 4m Inflatable went like stink with that on.(Thats the boat and engine that a couple of us wakeboarded behind)

Hugh Jardon · 19 October 2005, 17:45

Quote:

Originally Posted by anthony

Yes i will be carrying the boat and engine in the car.So would a 2 stroke be the best option?I have narrowed down my choice to:

15hp 2 stroke tohatsu/yamaha (37kg)

15hp 4 stroke suzuki (45kg)

18hp 2 stroke tohatsu (37kg)

20hp 4 stroke honda (46kg)

25hp 2 stroke tohatsu/yamaha (48kg)

does anyone have any comments about this engines.

yes i do have some launch wheels for the boat.

a couple of questions

does the boat rolled up fit in the car, if it does is there room for the engine comfortably as well.

my qs 3.4 just fits in the landy width wise and the 15 yam fits just inside widthway also

if you can go with 25 and get two props, i have one for towing toys and banging on the plane and one for high speed and cruising, and infact i have a third in the middle of these.

on a sib you can get away with a coarse pitch as the boats are so light and for me this gives me speed and cruising comfort.

as for going flat out, it is fab fun and sib surfing in big swells is the best

have fun