How Fast will a 2HP outboard push a 2.7m Sib in calm water

[PeterInSa]

Why i ask is that my 4HP 2 stroke is heavy have not measured it but to me around 35KG, plus a separate 10Lt fuel tank taking up room in my sib.

Note have yet to try the 4HP on my sib previous an electric motor and lithium battery.

Compared to a 2HP of 9.7Kg weight including tank plus extra weight of 1.5LT fuel plus 2LT of backup fuel/container

Reason for the question:
Space in the sib for the 10lt fuel tank
Weight of the 4HP motor compared to the 2HP.
Space in our Campervan for the 4HP/Tank compared to the 2HP and a 4LT of fuel.

Note my 4HP has Forward, Neutral and reverse, 2HP has Forward only, U turn the engine around for reverse and with low revs the prop does not turn.

Thanks for comments

Peter

[beamishken]

Don't know what 4hp 2 stroke you have at 35kg? My yamaha 5hp (same as the 4) is 21kg & my 8hp is 27kg.
I think the yam 2B is around 17kg but mercury/mariner do a very similar engine to yamahas 2b which is 3.3hp both the merc/mariner and the yamahas have integral tanks so no need to carry a 10lt tank
The 4hp up have f-n-r the smaller engines are 360° reverse

[PeterInSa]

Weighed it, was around 10Kg out its 25.5KG a 4HP 1980 version with little use but serviced on a regular/yearly basis.

others in comparison... 9.7Kg 3.6HP
https://www.gtmall.com.au/new-design...SABEgLmiPD_BwE

and 10Kg... 2HP
https://www.boatsonline.com.au/boats...utboard/147219

and with a Hangkai 3.5HP ( older model)looks oK to me
https://sosiski.com/post/qsjGH6JYPm4...t-2-3m-12km-h/

But service on Oz could be a problem....

[willk]

Approx. 5kts.

[beamishken]

Originally Posted by PeterInSa

Weighed it, was around 10Kg out its 25.5KG a 4HP 1980 version with little use but serviced on a regular/yearly basis.

others in comparison... 9.7Kg 3.6HP
https://www.gtmall.com.au/new-design...SABEgLmiPD_BwE

and 10Kg... 2HP
https://www.boatsonline.com.au/boats...utboard/147219

and with a Hangkai 3.5HP ( older model)looks oK to me
https://sosiski.com/post/qsjGH6JYPm4...t-2-3m-12km-h/

But service on Oz could be a problem....

Personally I wouldn't give any of those Chinese engines transom room, I'd imagine your almost 40yo 4hp would be more reliable.
The lightest mainstream engine will be something like the yam 2B or the merc mariner 3.3.
Sorry if this isn't answering your question about speed but I think you have more to consider than just the speed/ weight from one of those engines you are considering

[PeterInSa]

Small Mers/Yam go for around $400aud, year of manufacturer in the distant distant past. When I purchased my 2nd hand 4HP Merc in the distant past had problems with it running, no compression found out the bore was scored, piston NBG etc and I had to do a complete rebuild, 30 years later I do not want to do this with another motor.

But a name brand eg an old old merc will still have good resale value, not so, an as new Parsan/Hangkai.

And in Oz dealers will not be able to sell 2 strokes motors after July 2018 I believe, wonder when US will do the same so Chinese parts for these motors may dry up. Not so parts for Merc with so many still around.

And have to convince the other half I need another small motor??

[Mikefule]

Originally Posted by willk

Approx. 5kts.

Sounds about right. I have a 1.5 electric Torqeedo which pushes a heavy sailing dinghy at 5 mph (mph not knots) mast up, sail down, into a gently breeze. I also used to have a 3 hp 2 stroke that would just about get my old SIB (somewhere around 3.2 metres?) onto the plane, one up on perfectly flat water. The OP will be limited by immersed hull speed as there will not be enough power to get up onto the plane. 5 or 6 mph should be achievable. Twice as fast as rowing, and much easier!

[PeterInSa]

Ended up buying a Merc 3.3 in good condition with Neutral and Forward gear position($350 aud) so should be relatively late model ie in the last 10 years, this motor was used as a backup on a 12ft Tinnie.

Reason why I did not go ahead with a Hangkai were:

The Pull rope was thin and would wear out quickly.
The Pull rope assembly was small compared to the merc and a piece could come loose quiet easily, but can be fixed.

Above has a get around in that the motor comes with a spare pull rope assembly (and tools)that you take with you and can easily change on the water.

Unit has a rubber prime button that can wear out similar to a petrol lawn mower ( not a deal breaker)

But the main concern is the Block, and the quality of. Have not come across anyone with a Chines outboard that has done a lot of hours.

2 local repair'ers said they would not touch Chines OB's, 2 others said they would repair if necessary but possibly more time involved because they did not know the motor.

If you have a Hangkai and have not see UTube Vids below they are interesting and informing.

https://www.youtube.com/watch?v=322Aq735A9c

https://www.youtube.com/watch?v=3Qz2eyqFoy8