How fast? - Page 2

thornbackflound · 27 July 2009, 20:01

Quote:

Originally Posted by lightning

About 0.7hp would be my estimate.

Arh, many thanks ,well i won t be getting any g forces with that speed ,LOL

lightning · 27 July 2009, 21:19

I looked on You Tube and the Mariner 3.3/3.5hp seems to go quite well when fitted to a small craft with one or two people on board.

MikeP · 27 July 2009, 22:00

Hmm,

We've just had our first blast around Bristol Harbour with our 3.1m Zodiac Zoom - on a lovely sunny evening after work (a minor miracle getting out in time !)

This is the first time we've opened our 4HP Mariner up as we're still running it in, but I *think* we got onto the plane (certainly noticed the change in attitude as per the other Bristol Harbour Hooligan).

However, elation was swiftly dampened when we were overtaken by a rowing boat.

Admittedly manned by 8 burly blokes using two hands on a single oar each, but it was still a rowing boat.

Harumph.

lightning · 28 July 2009, 08:43

I just had a similar experience with my new Zodiac 285s/Mariner 6hp. It seems that you can get to about 5mph with no problem and hardly any RPM. Accelerating after that raises the bow considerably but does not increase the speed much, until you get it "on the plane", and then it's quite a bit faster.
The maximum displacement speed on my 285s is given as 12mph, which seems to be about what you can get with a 4/5/6hp engine. (I have not managed this, but have been unable to try, as I've only been on the canal so far)
I would imagine that an 8-man rowing boat would be capable of similar speeds.

MikeP · 28 July 2009, 21:34

Youtube and I have been fighting all day over this one, but for anyone interested vaguely in seeing Bristol Harbour and my bald spot, here's a short precis of our adventure Monday evening.

http://www.youtube.com/watch?v=MAH_5Oug4jU

On an ironic note, after we'd got back to base, I checked the fuel level in the outboard and noticed we were about two teaspoons away from breaking out the oars. Our previous couple of outings having been on the 4mph canal and river system, and I had started to think we could be the proud owners of an infinitely refilling fuel tank as we seemed to use so little petrol and could spend a good couple of hours plus out on the canal without worrying about go juice.

Funnily enough, it turns out that if you turn up the revs, you chew through the gas. I never would have thought :-)

On a serious note, if we don't kit ourselves up with an external fuel tank, we're faced with doing a refuel from the placcy 5 litre can on the water. This doesn't feel intuitively safe to me - but am I being a bit over cautious ??

Poly · 28 July 2009, 21:41

Quote:

Originally Posted by MikeP

On a serious note, if we don't kit ourselves up with an external fuel tank, we're faced with doing a refuel from the placcy 5 litre can on the water. This doesn't feel intuitively safe to me - but am I being a bit over cautious ??

Whether it is actually unsafe or not is a matter for debate (and might depend on where your filler is etc), But its certainly a PITA and likely to be messy in anything but ideal conditions.

MikeP · 28 July 2009, 22:00

My current refueling scenarios are based on being tied up to a bit of bank somewhere - be it in the Bristol floating harbour or on the canal or non-tidal river Avon. Not a challenging environment for having a nice cup of tea, but do the same gut feel metrics apply to sloshing more petrol into your outboard ? Our little 4HP Mariner has a top filling tank which is easy enough to deal with on dry land, but I guess I'm more concerned about spillage into the water than anything else.

Actually, having re-read the above back to myself, I think that refuelling on the water is a bad idea full stop as a spillage will inevitably be bad. So there's a point to note when buying your first outboard motor - how big is the fuel tank!

Back down to Saltford marina next week to look into external fuel tanks then.....

Sharkbyte · 28 July 2009, 22:13

Careful MikeP

What has PrairieTuber said about laying music tracks onto SIB Vids?

You know it interferes something dreadful with his hearing aid.

Crazy kids!

;-)

Bigmuz7 · 28 July 2009, 22:30

Quote:

Originally Posted by lightning

About 0.7hp would be my estimate.

..

Poly · 29 July 2009, 07:25

Quote:

Originally Posted by MikeP

My current refueling scenarios are based on being tied up to a bit of bank somewhere - be it in the Bristol floating harbour or on the canal or non-tidal river Avon. Not a challenging environment for having a nice cup of tea, but do the same gut feel metrics apply to sloshing more petrol into your outboard ? Our little 4HP Mariner has a top filling tank which is easy enough to deal with on dry land, but I guess I'm more concerned about spillage into the water than anything else.

Actually, having re-read the above back to myself, I think that refuelling on the water is a bad idea full stop as a spillage will inevitably be bad. So there's a point to note when buying your first outboard motor - how big is the fuel tank!

Back down to Saltford marina next week to look into external fuel tanks then.....

Ah OK. Small boat even tied up with all the weight at the back it will be a bit wobbly you will almost certainly spill some trying to get it to pour out of a can (they never flow well do they - although I notice someone advertising a new "spout" in all the boating media to "solve this problem"). The amount you spill will not be Exxon Valdese scale, probably won't be a particular fire hazard etc - so if I had to - I would. But if everyone did it all the time the world would be somewhat less pleasant (and within a Harbour/Canal you seriously risk upsetting the authorities - who can usually issue heavy fines for pollution).

If your outboard has a fitting for an optional eternal tank I would look at that (a small 12L tank is probably plenty). If it doesn't it may not be that easy to retro fit - and I would then look at ways of filling through the top that don't involve "pouring". i.e. a small hand pump. There are syphon devices around but that will mean holding the can above the engine - nicer if you can leave it on the deck - with a hose plumbed in (or on a quick release connector).

lightning · 29 July 2009, 07:34

The Mariner/Mercury 4hp does have the facility to fit an external fuel tank, I've got the 6hp which looks the same, but comes with the external tank. This holds 12 litres and has a gauge on it so you can see how much is left.
On holiday we had the use of a small boat with engine and I had to refuel that a few times while on the water. It's tricky as you have to stand up in the boat so you can see when the tank is full. You also need a funnel really to avoid spillage.
I'd say go for the external tank.
The fuel pipe that it comes with is long enough to put it under the bench seat.

Poly · 29 July 2009, 07:46

Quote:

Originally Posted by lightning

This holds 12 litres and has a gauge on it so you can see how much is left.

Be wary of putting too much faith in these - my experience is they can "jam" leading you to believe you have more fuel than you do.

lightning · 29 July 2009, 08:20

This one is very simple, just a float with a hole in the middle and a twisted metal rod connected to the gauge, as the float rises the rod turns and the needle moves. It's not very precise though.
However you can see the fuel level by looking at the tank itself, as it's visible through the plastic.