Auxillary Motor

cityfish · October 18, 2011, 09:04:07 CET

Hi Guys,

I need some advise regarding what size the auxillary motor should be for an 19ft Shetland with cabin. The main motor is 115HP. Thanks

kris · October 18, 2011, 11:18:06 CET

Hi cityfish,

At that size of boat I think that a minimum of 5hp is a must. But an 8 or 9.9hp would be a better option. Your decision should be primarily based on how far out you normally go...as a difference between a 5hp or a 9.9hp can be of 1 or 2 knots (maybe 3)...and that means adding an extra 2 or 3 hours coming in if you are really far out.. Another factor you should consider is how much persons you normally are and how much things / weight you normally take with you.

Hope this was helpful...

cityfish · October 20, 2011, 18:53:16 CET

Thanks Kris!

benri · October 20, 2011, 19:06:00 CET

Wish I could help Cityfish but apparently there is no hard and fast rule for an auxiliary motor, it's unfortunately more a case of trial and error

If it can help my boat is a 19 footer with a 140hp 4 stroke. I have an auxiliary 8hp Yamaha Enduro which in calm seas will reach up to 8 knots maximum. In rough weather it's only a dead weight I guess.

kris · October 20, 2011, 20:23:55 CET

No Problem city fish.

I can give you an idea also. I have a 15ft boat which weighs about 400kg (with motor). If we are 3 persons on board I can manage 4.5 knots with my 3.5hp 2 stroke auxilliary outboard.

toxictuna · October 22, 2011, 16:07:01 CET

21ft bayliner with an yamaha enduro standard prop 8hp 2 stroke - 5 knots good weather.

cityfish · October 22, 2011, 16:37:22 CET

Thanks all of you for your advise

kris · October 23, 2011, 11:31:16 CET

cityfish one more thing you should consider is whether or not you are going to leave your auxiliary motor on board. Theft of small outboards is a big problem...meaning that you should either opt for a less heavy outboard and carry it with you...or else you should lock it up safely in a compartment/bolt in to your boat etc

Note that you should also check the correct position on how you should 'store' your outboard as there is a difference between 2 stroke and 4 stroke outboards...as if I am not mistaken, 4 strokes should not be placed on the floor with the head facing upwards for a long time but should be stored in an upright position because of the engine and gear oil.

Destination Sea · October 23, 2011, 18:15:18 CET

hi kris i have a 17ft about 1100kgs with a9.8 . i see about 5.5 knots max 6

baghira · October 23, 2011, 21:31:19 CET

Dinghi 16foot.... auxilliary 2 x extendible pedals = .001 of a knot if sea is not rough..... or else towed by some lucky member of this forum...

Wish I had space for one

fisheye · October 24, 2011, 07:25:22 CET

there are ways how to fix an auxillary motor even on small ribs give a look at this site, page 11 http://www.ibs-boats.com/download/ibs-spares-catalogue-08.pdf

baghira · October 24, 2011, 09:53:45 CET

Not if the back is like mine......