Raggie to Mobo.

[Mavro]

Hi guys,

I've got a good friend who has just bought a 31ft cabin cruiser to use in the rivers near us - but we are already talking about going further afield - coastal trips, maybe cross channel.

I'm pretty comfortable skippering sailing yachts up to 47ft. I've got my Day Skipper and about 3500 miles under my belt (most of it along the South Coast, but some Med). I've done a Fastnet (as crew) and I've also got YachtMaster theory.

All of this has been focused on sailing apart (apart from Power Boat 2). Although a lot of the navigation etc is transferrable I'm not sure what I might be missing and if there is any value in getting some motor boat specific training. Either doing a Day Skipper Motor or some kind of conversion course?

Has anybody made a similar transition? Were there any surprises or was it pretty straight forward. I don't know what I don't know if that makes sense. I was hoping to get some pointers on what the likely gaps would be in my knowledge with the background that I have.

 

[oceanfroggie]

One difference is passage planing. Mobo does not necessarily have to worry as much about tidal stream impact on passage time. Weather and sea state is another area of difference because what may be comfortable under sail, may not be comfortable under power in a 'rolley' mobo without a sail to limit boat movement. Some times in a mobo one plans a passage for ride comfort rather than shortest time. For example, timing a trip to run against a tidal stream because a stiff breeze is blowing with the tide.

Sometimes a poor sea state may limit a mobo to displacement speeds depending on the swell, wave length, wind, etc (e.g. avoid violent slamming in head sea). Basically mobos move around much more with significant wave action than a keel boat under sail. Obviously fuel range on a mobo, especially a planing boat is much more of a planning issue that a yacht.

 

[Mavro]

Thanks. That is quite a different mind-set. I wouldn't have considered that but it makes sense.

 

[kashurst]

approaching and leaving moorings is different - but not difficult, you operate mobo controls in a different way to a sailing boat when mooring up. Might be worth getting some lessons. Shaft drive boats behave differently to outdrive boats too.
The other thing to be super vigilant about is the condition of the fuel tanks and all the fuel pipes, filters, engine cooling etc. There's no free ride home on a mobo if you loose an engine(s). If the boat has had little sea use, then its likely the first few times you go out onto the sea with a few waves you may be unfortunate and get a few problems. Usually blocked fuel filters or broken impellers. Make sure you/crew know how to change them and carry spares. Before heading off to the channel islands etc, do a few test runs out at sea, but not very far from home 1/2m or so out, throw the boat about a bit to see what she can do, This will shake everything up and any weaknesses or fuel/cooling issues will reveal themselves. Mobos when planning don't roll much at all, however going slowly they can roll about a lot. So the last 1/4 mile or so leaving or entering a harbour make sure everyone is sitting down and holding on to something.

 

[Robin]

When we lived and cruised on a 47 ft trawler style, semi displacement motor yacht it had more windage when berthing than full sail on our previous 41ft sailboat and at over 20 tons was not easily bullied with push and shove. You do get used to it eventually. Also need to remember bumping bottom with props is expensive where a keel gives some protection. Flybridges can be very wet places in choppy water. Initially too I took time to accept that inertia determined where the boat actually moved, not which direction it was merely pointed, so in close quarters stop moving first off then turn, stop the rotational turn, only then move off again in required direction. .

 

[oceanfroggie]

Thanks. That is quite a different mind-set. I wouldn't have considered that but it makes sense.

Your welcome

PS: Motor users need to keep good look out to avoid pots or choose route to avoid, especially at night, or rough sea state when you can't spot them as easily. Fouling a prop with a pots line is a bigger issue for a mobo. Some shaft drive mobo'ers who cruise routes where pots are prevalent fit rope cutters to their prop shafts.

 

[stuartwineberg]

One difference is passage planing. Mobo does not necessarily have to worry as much about tidal stream impact on passage time. Weather and sea state is another area of difference because what may be comfortable under sail, may not be comfortable under power in a 'rolley' mobo without a sail to limit boat movement. Some times in a mobo one plans a passage for ride comfort rather than shortest time. For example, timing a trip to run against a tidal stream because a stiff breeze is blowing with the tide.

Sometimes a poor sea state may limit a mobo to displacement speeds depending on the swell, wave length, wind, etc (e.g. avoid violent slamming in head sea). Basically mobos move around much more with significant wave action than a keel boat under sail. Obviously fuel range on a mobo, especially a planing boat is much more of a planning issue that a yacht.

This is good advice. Another consideration is whether you will need to turn beam on to a sea. I aborted a trip into Beaulieu because the short leg into the river was causing unacceptable rolling in my 25 footer as I crossed the waves. I note that the boat is a cabin cruiser designed mainly for river use. Does it have decent power to achieve planing speeds? Many power boats were built in multiple versions - some with displacement power engines and some with much bigger units. Single engined power boats can be very interesting to handle. A big prop can have lots of prop walk, rudders tend to be small, lack of keel means lot of wind effect especially with a big high sided cabin. If you have a bowthruster it can help a lot. Twin engined units are also very different - you have the ability there to drive a bit like a tank - using one forward, one reverse to aid turns and so on.

 

[tom52]

I switched to mobo a couple of years ago after 25 years sailing.
Without a keel and no steadying effect from sails anything above F4 in the open sea for more than a couple of hours is a challenge for a 31 foot mobo.
Opportunities for significant sea voyages for small mobos are therefore restricted in British waters to the rare spells of settled fair weather.
For close quarter manoeuvring rudders are small, windage is big and engines are powerful. Drifting slowly into your berth
whilst still having steering way at hardly 1/2 a knot is no longer an option ! Different techniques are required.

 

[dragoon]

We did the same, but I still rent sailing boats from time to time. Here's a list of a few observations;

Sailing boats are more comfortable in heavier weather.
Motor boats need less tidal planning - the rate of tide is less significant when you are packing a few hundred horsepower.
Motor boats don't have an independent form of propulsion, so make sure your servicing is up together.
Motor boats on a nice day are going to be a lot quicker A to B, generally speaking.
We don't have a bowthruster, but 2 engines makes mooring a lot easier, especially in a blow.
Motorboats tend to be blessed with space compared to a sailing boat - at least the boats I've been on.
Depending on keel arrangements , you can go shallower in a lot of motor boats, but it can be more expensive if you hit the bottom!
Most motorboats are drier in poor conditions (even flybridges tend to have a lower helm), but you still might not go out due to the rolling you'll experience.
Motor boats seem to have more sociable seating areas - I've never found yacht cockpits to be especially comfortable - at least on smaller vessels.

I don't know as you need any formal training necessarily, but you might want to ask someone with some experience of motor boats to join for a couple of trips, especially whilst you get familiar with the close quarters maneuvering.

Oh, and the other thing - all the friends you wave at when you were sailing, will ignore you now

 

[Mavro]

Thank you everyone this has been really helpful. I understand all of the points made but it has made me realise I would feel more confident if I get a little extra training before venturing out too far. My engine mechanics could do with a brush up and learning close quarters maneuvering from someone who knows the right approach will likely be a lot less expensive in the long run.

Thanks and see you on the water