Sabb 10 hp Diiesel boat

[JCBOATING]

Would a 10hp Sabb diesel be able to push a 20 foot small boat comfortably in a tidal estuary say such as the river crouch say to 5 to 6 knt`s and then perhaps to shore for fishing etc . these engines appear very strong just wondering if any body could give me advise would this be suitable for this type of trip. Thank you Jeremy

 

[RichardS]

I think this really needs to be posted in the PBO forum.

You might not get the answers you are expecting in this one. :ambivalence:

Richard

 

[2nd_apprentice]

Well a 20ft boat will always struggle due to its maximum hull speed which is going to be less than 6 knots (depending on its waterline length). No point in fighting the tide really: no matter how powerful your engine, you're going to go backwards.
As for the Sabb 10 hp, it does have a good reputation but it's also rather ancient. Sourcing spare parts might become a major problem, so keep that in mind!

 

[Woodlouse]

Depends on the weight of the boat too really rather than the length.

 

[2nd_apprentice]

Not if we're talking about a displacement hull:

 

[Woodlouse]

Not if we're talking about a displacement hull:

To some extent yes, but also no. Waterline length in a displacement boat only produces a theoretical maximum hull speed. That speed can and will be exceeded with a sufficient power to weight ratio.

 

[Mirror Painter]

Thank god Lake Sailor isn't here to be upset by this

 

[JCBOATING]

I am lost ,ok a shade new to boating yet an adventurous ,no speed for this launch is needed I did find a clip on you tube of a 10 hp of the type it appeared making good work of an old wooden fishing boat all I am concerned about is not being able to push an out tide and having to throw anchor and wait for the turn of the tide. I have owned and seen many diesel engines non marine, but never this torque at such a low rev. The hull on the subject vessel is quite sharp in appearance "pardon the laymen term. " To get this thread back to it point could she push back say on an out tide the vessel may weigh as an estimation with it cabin of wood about a miro plus type boat 1.3 , say a guest at one miro plus with an 40 hp outboard and a third again . The engine I have read up on could push a narrow boat on 40 foot in still water. I am going to try to post a link to a working example .I really appreciate comment and advise and take my boating very seriously . Thank you for any help.https://www.youtube.com/watch?v=efPJqfl5kPs
Jeremy

 

[nortada]

Many serious sailors don't access The Forum so you may get a better response if you reopen this debate in PBO Reader to Reader.

That said the 8 posts to date just about answer your questions.

 

[K-ron]

As for the Sabb 10 hp, it does have a good reputation but it's also rather ancient. Sourcing spare parts might become a major problem, so keep that in mind!

Sabb stopped making the 10HP in 2002 a run of 24 000 units and most spares are readily available from Sleeman Hawken.
My Sabb happily pushes my 7.5 ton Nicholson 32 which weighs near enough 10 ton with all our cruising gear to over 5 knots but speed is greatly reduced whilst running head to wind. Also it's worth adding the engine is quite a lump, weighing in at 200kg.

Kieran

 

[JCBOATING]

Kieran what HP is your sabb engine ?

Thank you

Jeremy

 

[K-ron]

It's a model G 10HP.
I just finished rebuilding my one, here is a link to the thread

http://www.ybw.com/forums/showthread.php?472265-Rebuilding-a-1968-Sabb-model-GG

If you are thinking about buying one of these engines I would be happy to give you a few pointers of things to look for that may help to ascertain the general condition of the engine.

Kieran

 

[AntarcticPilot]

The situation is that for all displacement hulls, there is a point where the power required to go faster starts to increase rapidly. As other have said, thats usually (for all common hull forms) somewhere near 1.4 times the square root of the waterline length in feet. More power won't make you go significantly faster, but will burn a lot more fuel! This restriction arises from the interaction of bow and quarter waves with the hull, and can be thought of as arising from the power needed to "climb" the bow wave. The only way of getting away from this restriction is to have a planing hull form, which rises out of the water to allow higher speeds. However, planing hulls may not be suitable for what you want to do.

You also have problems in transmitting the power to the water; again this is to do with the RPM of the shaft and the diameter and pitch of the propellor. The maximum diameter will be dictated by the hull shape; this is a less important restriction, but may be relevant.


A third point is that engines push boats through the water, so the maximum speeds etc. all apply to speed through the water. If the water itself if moving, then the speed at which it is moving must be added or subtracted from the maximum speed available from the hull/engine/propellor combination. No 20' displacement boat is going to exceed 5 or 6 knots no matter what, so if there's a 5 knot tide running against you, you might as well save fuel by anchoring and waiting for the tide to turn! This is where planning your trips to work with the tide is important - tides are highly predictable! What is important is that there is sufficient excess power to push through waves; this is the only reason to look for power above that required to push the boat at "hull speed".

I'd imagine that on a 20' boat, a 10hp Sabb would be a great engine for what you're doing. They are reliable and simple, and others have said that parts are available. But there really isn't much to go wrong - they are seriously over-engineered! We had a smaller one on a 27' yacht in the 1960s, and never complained about lack of power - I suspect Norwegian horses are bigger and stronger than British ones More seriously, I have a 28HP engine on a 31' boat, and have rarely if ever run it at full power except once in a while as an Italian tune-up!

 

[Tranona]

As your video shows these engines were built to power heavy inshore fishing boats. The secret is the large slow turning prop, rather than the HP of the engine. They were very popular in the UK 20-50 years ago, particularly in boats such as the Plymouth Pilot, whose builder was the agent at the time.. so, yes in the right sort of boat it will do the job. However, you have to be prepared for a very simple almost crude engine and make sure all the fillings and crowns in your teeth are secure. The UK equivalent was the Lister 12HP aircooled - even cruder and more noisy! The Sabb is probably the better of the two.

 

[LittleSister]

10 hp is quite adequate for a normal 20 foot boat in the River Crouch, in my view.

(I sailed a friend's Sabb powered Cornish Crabber (24ft plus bowsprit, IIRC), and it seemed perfectly adequate (at least in the relatively calm conditions I encountered). My heavyweight 23ft sailing boat has 14hp and that's more than ample.)

I don't think you will get 6 knots (= about 7mph), though, because this is faster than the nominal max hull speed of a displacement (normal) hull of that length (as explained above). To get that speed you would need any one of the following (a) a longer hull, or (b) a much more powerful (and thirsty) engine, or (c) a planing hull (which will probably need more power and less weight than the Sabb, anyway, to get up on the plane).