Lowest speed under engine

[walker]

I wonder if I might again plunder forumites brains for a bit of advice. Being generally a bit shorted handed, on a recent first trip on an unfamiliar boat we planned to put into practice previous advice of motoring gently forward against a spring while sorting out other lines. But before getting the chance to have a go, noticed that minimum speed forward with engine engaged seems to be about 3.5 knots, which seemed a bit much for aforementioned manouevre on finger pontoons so opted instead for occasionally undignified scramble to get fore and aft lines ashore. My question is, although I am sure 3.5kts is higher than minimum speed on previous boats I have been on (all smaller, with correspondingly smaller engines) is it within a 'normal' acceptable range of minimum speeds, or is it likely something needs adjusting?

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by walker on 13/12/2004 15:47 (server time).</FONT></P>

 

[sailorman]

my slo spd is similar to yours,
it is possilbe to use "neutral" & coast then use astern gear, get a line on centre cleat first made short & then control boat using forward & astern as req. especially in locks

<hr width=100% size=1>Mines a Crocodile sandwich & make it Snappy

 

[walker]

Thanks Sailorman - the hope was to be able to put engine in lowest forard speed then leave it so that I could hep with the other lines but with that much 'thrust' worried about motoring off with the pontoon - although thinking about it, that must be as nothing compared with a good breeze blowing me off so perhaps worrying unnecessarily.

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[snowleopard]

if you have a rev counter, check the engine is doing no more than 7-800 rpm.

a heavy boat with lightish engine may do a little under 2 knots on tickover, typical AWBs with big engines nearer your 3.5 figure. to achieve a slow approach, just put it in and out of gear without revving.

best advice i've heard for berthing is "as slow as you can, as fast as you must", i.e. never use more speed than absolutely essential. high-speed charges and loads of reverse are for macho idiots.

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[SlowlyButSurely]

If it's an AWB I think you'll probably be OK because it's not so much the speed at tickover that's important, it's the amount of thrust; ie. your easily driven hull will go faster than a heavy displacement boat would with the same engine revs and when stationary you won't rip the pontoon off its piles. Give it a go and see if the strain on the rope seems OK.

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[Chris_Robb]

>high-speed charges and loads of reverse are for macho idiots. <

Not if you have a long keeled boat. Its often the only way to do some really slick manouvers! Going too slow means you are effectively dead in the water.

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[Talbot]

<blockquote><font size=1>Quote from previous post:</font><hr>

high-speed charges and loads of reverse are for macho idiots.

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or for catamaran sailers with one engine and two rudders (and no low aspect ratio keel) trying to berth in windy conditions /forums/images/icons/crazy.gif

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[Guest]

Join the club !

My 40hp in a 25ft MS ..... gives me about 3 - 3.5 kts at slow speed.
So I let her come alongside coasting , get that spring ashore, slip into gear and helm few degrees so that arse tends into pontoon.
Now take time over all other lines as long as wind etc. is not blowing off pontoon.

The trick is MOMEMTUM ...... that is what strains / breaks lines etc. in this situation. If the boat is basically still when you engage fwd - there is not enough to get boat really moving ..... ok you have a fair bit of strain and thrust from the prop, but it will cavitate as it finds it cant move fwd anymore .... losing a significant amount of its power.

Look at the pontoon as well - designed to take full force of wind and tide etc. with boat alongside ...... far more than slow speed on the engine ..... and note that engine will be along the axis of the pontoon - not across it ......

My thought ..... try it - watching carefully for cleat strain etc.


<hr width=100% size=1>Cheers Nigel ..... <A target="_blank" HREF=http://www.geocities.com/solentlifeuk/>http://www.geocities.com/solentlifeuk/</A>

 

[Thistle]

Sorry ... a dumb question: what's an ABW? Thanks in anticipation.

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[charles_reed]

Under power at tick-over my boat does about 1.2 knots on the GPS and the log reads about 0.5.

The tick-over is set low enough that you have to give the Yanmar 2GM20 some throttle to start when warm (when cold it's no problem the mixture automatically enriches).

Every boat differs, but I'd check if the reading is accurate, though logs usually under-read at low speeds.

I usually get the 6 fenders and lines out before entering any entrance channel. In about 12 years of singlehanding I've found that the best tactic.

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[walker]

An AWB is I think an average white boat i.e the great majority of modern boats.

Ours is one of them, and from the replies here it seems as though our idle speed is at the high side of the normal range, but I shall take heart and test the pontoon -we are moving location at the beginning of next season so it will be a good time to try it!



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[Gunfleet]

Tell me about it. With the wind on certain points the only way to get my boat through it to berth is with a good old turn of speed. Then of course you have to find a way to get it off again! Nowadays it's more nerve wracking for people watching than it is for me. Of course then there's the problem of the tide which will 'trip' the bow if you don't watch it. It can get interesting in confined spaces.

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[sailorman]

Bav not AWB !.
our engine idles @ 850 RPM

<hr width=100% size=1>Mines a Crocodile sandwich & make it Snappy

 

[walker]

You mean its even sub-AWB?

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[wooslehunter]

Be interested to see if you big boat guys do the same as me. The method below works a treat for 26 foot single handed berthing.

Rig the mooring lines as normal plus an additional one. I take this from a cleat by the shrouds. Make a big loop and back under the safety lines to a winch - doesn't have to be a winch. I just hace one conveniently placed.

Coast in to the berth with blips of motor to correct if necessary. Once I'm close in I throw the loop ove a cleat, continue forward & pull in the slack. Once settled, I can motor against this rope with the tiller over to pull the stern in. The bow can't swing out too far & the boat's stable & going no-where. I then have all the time in the world to get the other lines on.

Everythings controlled from the cockpit so no running around or away from the tiller/engine controls.

Does it work on the 40 footer as well? Can't see why not.

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[walker]

Sounds basically very similar in principle to what people on here have advised me to do, except I would generally have one crew to take the spring ashore. But if I understand you correctly - shrouds cleat > shore > winch - in our boat that would make pretty well an equilateral triangle which I couldn't imagine motoring against without the bow pushing a long way off in which case I might be more in need of a roving fenderman than anything else so in our case if I needed to do it single handed I would be inclined to run the loop back to the spring cleat. The instructor on a recent course did show us how mobos throw two coils simultaneously to catch cleats but we were preoccupied trying to figure how to rig a noose to string him up from to take much notice.

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[Donalex]

Maybe your prop. Bruntons Autoprops constantly "change gear" to higher pitch settings as the boat gathers way - so you could be moving faster than a normal prop would give

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[BrendanS]

Going back to basics here. Once you've got the spring on, I don't think you'll have any problems with the prob thrust being too high

As long as it holds you against the pontoon, and you are well fendered, it will achieve the results you want.

<hr width=100% size=1>Me transmitte sursum, caledoni

 

[Chris_Robb]

Not something I have to worry about anymore!

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[Evadne]

I think it's all relative. What's slow for a lightweight boat is normal for a long keeled heavyweight. You have more momentum with a long-keeler at low speeds and anyway, 3.5 knots is closer to our top speed under power. Having seen how far up she rode when we hit a marina pontoon at about 2-3 knots, (gear cable snapped at an inappropriate moment,) I wouldn't want to do it any faster: she'd be over it and into the opposite berth!

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