Why a 20 hp Outboard

3 minute read

After some discussions on forums, it became obvious that I’d have to do a follow up post on why I got a 20 hp. Honda motor.

There was a few variables that went into the equation.

Weight, Cost and Horsepower.

I looked at the Torqeedo 4 kw motor. That in theory was a good idea, 8 hp. in cruise mode, 10 hp. thrust (which incidentally Lin and Larry said would be enough). This motor is about 20 kg. Then comes the batteries. The Torqeedo batteries are 24.3 kg. each, you require 2. These batteries are very expensive, so going with a lead-acid/AGM option you’d need 4 x 200 A/H batteries (Torqeedo batteries are 24V lithium). Finding space for these batteries would be a challenge in it’s own right. Not to mention that the costs would be very high for a setup like this and charging would be a challenge unless you’re in a marina. Even then it’s very easy to add petrol to a tank, start the motor and go. Not the same with batteries. This is also not a simple setup, it’s quite complicated and at odds with the rest of the boat. Incidentally I looked at the 10 kw motor too, that weighs 64kg and requires twice as many batteries, so twice the problem. Not to mention 3 times the cost without installation costs and brackets etc.

So the other option is to go for petrol. I wanted something that’s simple, that means manual tilt, tiller steer and pull start.

The Yamaha 9.9 hp. has been mentioned, I rejected that motor due to the fact that it’s electric start only (battery and more complication required), this motor also weights 49 - 52KG depending on the model. So not a lot of upside here.

Tohatsu is another one that was mentioned. The dealers proved challenging to get a quote from, at first. This lead me to wonder what support would be like, if they are in sales mode they are at their best, so they won’t get any better… The motor that was quoted was not only 20% more expensive than the Honda but also weighed 62 kg. It’s worth noting that this was a manual/electric start and also a manual/power tilt - which explains the weight.

Honda, I looked at the 8/10 hp which is the same motor just tuned differently, this was 48 kg. The 15/20 hp. which is the same motor just tuned differently at 52 kg.

These are the only motors I’ll mention as inboards were not an option due to the required hole(s) in the hull. Other manufacturers didn’t do 25” shafts.

At the end of the day the weight vs benefit ration landed me with Honda 20 hp 25” shaft, of course the dealer was fantastic too so that helps.

A quick note on electric inboards. The cost of the motor and batteries would have been 3 times the total of the outboard solution. I didn’t even bother to cost the installation of it. It was considered as a hypothetical case, but it was never really an option. This of course comes with the problem of where to store all those batteries. The same goes for electric POD motors.

Taking all of the above and possibly a lot of things I forgot about, it seemed that the sensible choice would be to go for 20 hp. over 8 hp. for a 4 kg. weight increase. The option to go with a smaller engine is always there too, not that you gain much by going smaller, maybe if I went for a 5 hp. motor it might have made a noticeable difference in weight. Taleisin is 8 tons when empty, the 8 hp. on the rubber ducky does the job but leaves a lot to be desired and certainly wont stop her in a hurry if it’s needed. I learnt that the hard way when I got defeated in the marina (see the post about it).


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