Size of Aux?

[Calne Diver]

OK quick question!

What size Aux would be enough to push round my 6.4m rib? And would I need xl length leg or anything!

Haven't had one before so just checking.

Thanks!

[Chris]

Rule of thumb is 1hp per meter. Ideally for a 6.5 I would look for 8hp ideally 2 stroke and yes you will probably need XL shaft to get tue best out of it. Look for the saildrive type as these are geared and propped for pushing large loads.

[Calne Diver]

Great, thanks! But how would I tell if an outboard on EBay for example is a saildrive?

[thomas]

Chances are that someone selling a long shaft will have it for a reason and know to advertivse it as long shaft.

I needed one for my raggie and found a 2006 yamaha 8hp 2 stroke, it was short shaft but as it was so new I bought it anyway and converted it to long shaft, cost well under £200 for all the bits I needed to convert it.


There are a couple on eBay at the moment if you do a search.

[BogMonster]

My 4hp aux is a long shaft (not XL - but a standard 4-6hp engine is short shaft) and it is fine on the transom of my Vipermax which has an XL shaft main engine. I doubt whether there are many XL shaft (25 inch) engines in this size range?

The only real difference on the Saildrive type engines is a fine pitch prop and sometimes a charging output to siphon off some electricity. May be just as easy to widen the search and change the prop?

[Courageous]

Have a 4hp Mariner Long shaft on my Valiant DR750. It's a 4 stroke and pushes the boat at 4 knots in a calm sea and that was with me alone. I'd not be over confident in its ability in a reasonable headwind or much of a sea though, or with 12 divers with full kit aboard, so I would go with Chris's advice.

[Chris]

I had a 4hp yam on my first 5 meter Osprey initially I had a STD shaft however I swapped it for a long shaft and it made a big difference to the effectiveness as the prop was then in clear water below the transom. Definately long shaft IMO.