I met a courteous mobo yesterday

[ProDave]

Minding our own business sailing our boat, a big mobo approaching us. As he got close he reduced speed and came down off the plane, passed us with a friendly wave, then put the power back on once he had gone passed. Clearly he did that to reduce his wake that we would encounter. It struck me as very professional and courteous seamanship. This is the first time i can remember someone being so considerate.

Anyone care to guess what the boat was?

 

[ashtead]

Border patrol cutter ?

 

[Frogmogman]

Lifeboat ?
Drug smuggler ?

 

[ProDave]

Lifeboat ?

Correct, one of the local all weather boats.

 

[Seastoke]

That might work in Scotland , but could not work on the south coast.

 

[Poignard]

[....]
Anyone care to guess what the boat was?

A French-owned one?

 

[Fire99]

Some of us are quite decent folk you know.. Plus my previous boat had sails so I see both sides of the sea (so to speak)

 

[[3889]]

Am I wrong in thinking planing mobos generate more wake in displacement mode? Personally I find mobos no less considerate than raggies. Like most things, it's down to the individual, not the vessel.

 

[oldgit]

Am I wrong in thinking planing mobos generate more wake in displacement mode? Personally I find mobos no less considerate than raggies. Like most things, it's down to the individual, not the vessel.

Nope...... at displacement speed any decent sized MoBo will generate very little wake compared to the "hole in the water" it leaves behind when planing.

 

[Alan S]

Big difference between a heavy semi-displacement hull like a lifeboat and a light planing speedboat hull. The latter will generate less wash at high speed than slow, but the opposite is the case with the former.

 

[greeny]

Normally no hole in the water when modern power boats are planing. Planing means they've got out of the hole. Much less wake than when pushing through the water at pre planing speeds. IMHOAE.

 

[Elessar]

Am I wrong in thinking planing mobos generate more wake in displacement mode? Personally I find mobos no less considerate than raggies. Like most things, it's down to the individual, not the vessel.

Ok back to basics.
As a boat moves in displacement mode it creates a bow wave.
The faster the boat moves the longer the wave.
Once the wave reaches the back of the hull, that is the hull speed.
Up to this speed there is very little wake.
Thus the bigger the boat the faster it can go in displacement speed.

Add more power and you get very little extra speed. The bow raises and the boat is climbing a hill. It is using lots of fuel and causing lots of wake. This is the standard mode for RIBs going up a river sticking to 6 knots!

Add yet more power and the stern lifts and the boat is planing. A light boat when planing creates very little wake. If you have a tender with a 6hp or more you will feel this - move your weight forward and the back seems to unstick and you go much faster.

Motor cruisers generally don’t plane like a small RIB or fast race boat and create quite a big wake.

So in my boat,
up to 7 knots - v little wake
7 knots to 18 knots - monster wake
18 knots and above - wake

So the last thing you want is for motor cruisers to slow down a bit whilst trying to be polite. It’s true displacement speed or keep going fast.

 

[ProDave]

Interesting information about the different types of boat and how they behave.

All I was trying to say is I was very impressed with the seamanship of the skipper, he obviously (as you would expect) knew his boat and knew what other types of craft, e.g. a small sailing boat, would experience. Not only did he slow down, but made a course alteration so he passed parallel to us, not cutting across our bow at an angle.

We don't see many motor cruisers, most of the mobos's we see are ribs or small fishing boats and a few regular tourist trip boats. None of those seem to show any consideration for other boats, they are happy to blat about at full speed often crossing right across our bow leaving us a huge wake to climb over. It was just pleasant to experience better seamanship.

 

[Chiara’s slave]

Normally no hole in the water when modern power boats are planing. Planing means they've got out of the hole. Much less wake than when pushing through the water at pre planing speeds. IMHOAE.

I find the very worst is forced speed, just before full planing.

 

[ProMariner]

Had a near death experience once when Peterhead lifeboat passed a work site I was on, in the inner harbour, at full chat. I was doing an oil change, and the engine on my 30 ton boat came up and whacked me on the head. He was on a shout, but just to a broken down boat offshore, think he just liked making waves. Glad to hear they are being nicer now, there is a time for full speed ahead, and a time for being considerate. If you save one boat, but kill another one in the process, does it cancel out?

 

[ProDave]

He was on a shout, but just to a broken down boat offshore, think he just liked making waves

I did suspect if the boat that passed me had been on a shout, he probably would not have slowed down?

 

[Juan Twothree]

I did suspect if the boat that passed me had been on a shout, he probably would not have slowed down?

He probably would have slowed down.

There are very few situations where saving a few seconds on the transit to the casualty is going to make any difference to the outcome.

 

[gordmac]

I wonder how much fuel it uses to drop of the plane then climb back up?

 

[scottie]

worst I have ever experienced was a submarine passing close ahead That was more like a sink hole in the water it washed everything of f the the coachroof
we just dropped into the hole no wave as such just a vertical drop of several feet

 

[ChromeDome]

Always aim not to disturb others on the water, in our MOBO. However, there are waves on the water and all boaters should be prepared to accept that - even if created by vessels moving.

A flappy thingy sailor once accused me of "taking his wind" after passing him at 6-7 knots at 50 m distance, when he was struggling to get his boat to move forward.

Puzzled by that - I wasn't aware the wind is owned by anybody.