engines for 520 supercat FC

Post Reply
jptresfon
Posts: 65
Joined: Tue Oct 22, 2013 2:32 pm
Boat: 520 Supercat "Adamastor"
Best catch: 93kg yellowfin

engines for 520 supercat FC

Post by jptresfon » Sat Apr 11, 2020 5:29 pm

Hi guys

I have one of the older lightweight supercat 520's, with a forward consol. Awesome boat and so easy to use.
Thinking of replacing the 60hp 2 stroke yammies i have on currently with 4 strokes at some point. Its not so much a fuel consumption issue, just makes life easier all round when doing tuna trips etc as don't have to carry so much fuel, and space always a premium on small boats.

What is the general consensus on best option - go for 60hp or 70hp option?
Extra power is always better i suppose, not that there is any issue with 60's.

Can anyone running 70hp 4 stroke yammies confirm how well the boats handle the extra weight at back. This being my biggest concern. I do have a false transom so water wouldn't get on deck, but worried that engines might sit too low in water and this wouldn't be too good for them i guess.

Not sure what the weight diff is between 60hp 2 strokes and 70hp 4 strokes. Seem quite hard to find this info online.

I have always been a yamaha person, so haven't considered the others - should I ?

Guess one of the downsides of the lockdown is we get to sit and dream about fishing and that somehow always costs us money :lol:

thanks in advance!

snack
Posts: 239
Joined: Tue Oct 02, 2012 10:15 am
Boat: 4,2m Gemini Waverider & 40 Yamaha

Re: engines for 520 supercat FC

Post by snack » Mon Apr 13, 2020 11:23 am

I spoke to the boating shed and magson and both recommended going with the 70. The 70 weighs the same as the 60.

I currently have a pair of 70 evinrudes on my FC that weigh 120 each and haven’t experienced any issues with the weight. Will most likely need to redo the buoyancy certificate calculations due to the extra weight. The 70 weighs 114 kg and your two strokes about 100

jptresfon
Posts: 65
Joined: Tue Oct 22, 2013 2:32 pm
Boat: 520 Supercat "Adamastor"
Best catch: 93kg yellowfin

Re: engines for 520 supercat FC

Post by jptresfon » Mon Apr 13, 2020 10:27 pm

Thanks for the input.

RyanH
Posts: 170
Joined: Wed Dec 02, 2015 7:01 pm
Boat: Ocean Runner 17
Best catch: The last one

Re: engines for 520 supercat FC

Post by RyanH » Wed May 27, 2020 7:31 pm

HI Jean, you can always replicate the extra weight of the 4-strokes by placing sand bags of equivalent weight in your splash well. I have just been doing something similar with a 620 project boat I have to work out fuel tank positions etc

jptresfon
Posts: 65
Joined: Tue Oct 22, 2013 2:32 pm
Boat: 520 Supercat "Adamastor"
Best catch: 93kg yellowfin

Re: engines for 520 supercat FC

Post by jptresfon » Thu Jun 11, 2020 1:48 pm

So ended up going for the yammie F70's.
Weight seems to not be an issue at all and they look perfect on the boat.

Initial tests give me 5knts troll speed at 1600 rpm and 20kts at 4200rpm. This pushing 15 pitch props.
Not sure of WOT rpm as need a couple more gentle hours on the engines to run in a bit first. So not sure yet if i need to consider 17 pitch props or if the 15's will be best.

Do these numbers sound about right?

Oh and did 16.5nm with 16.9L total fuel consumption which is great. I'm sure this will still improve a bit once they loosen up a bit.

jptresfon
Posts: 65
Joined: Tue Oct 22, 2013 2:32 pm
Boat: 520 Supercat "Adamastor"
Best catch: 93kg yellowfin

Re: engines for 520 supercat FC

Post by jptresfon » Fri Jun 19, 2020 2:52 pm

WOT rpm = 6200 @ 32kts
Cruising = 4200 rpm @ 20 kts
Trolling = 1600rpm @ 5kts

Fuel consumption on last trip was 41L for 40.5nm

Not sure if i should be looking at trying 17 pitch props or if these numbers suggest 15 pitch are about right

Any thoughts?

Post Reply

Return to “Outboard Reviews and Discussions”