anyone have a yamaha 50-70 hp comparisons ?

[stevej]

Thanks for that not sure what I was reading with the weights
probably should have been paying more attention to work

50kg would be a rather skinny bloke at the back lol

the yamaha 70 isn’t worth the upgrade , its never a simple solution with boats

[disorderly]

Have you looked into an ECU remap..?.you might be able to get 70hp out of your existing motor..

Isnt there a mob in melbourne that does it..?

[stevej]

Tbh I think they are black magic rubbish
the 70 makes it’s prop rated hp with different gearing

only way to make more hp safely is capacity and rpm increase
less safely increased timing and leaning the fuel mixtures.

I’ll just wait for Covid to ease off and decide on a bigger boat.
just wanted to keep this one as it’s a good all rounder for me and fits in a standard garage if I moved as I want to get back to civilisation eventually before retirement

I won’t have the monster shed forever

[ericcs]

looks the same with the cowling off
same bore size
same cc
different gear ratio

it’s only 20kg heavier dry which is offset by going to a lithium crank battery over the lead acid I have now

70-50 HP 1L Midrange Outboard Motors | Yamaha Outboards

us yamaha sites says they are al the same
just had a better read as at work the 70 has 300 rpm higher rev range and some more timing for the extra 10hp

the 70 also has a 16 valve head, as opposed to an 8 valve for the 50/60, and i believe, the 70 run's a bigger gearcase also!

[stevej]

Thanks for the info
still not enough of a increase to make it worthwhile

[gazza2006au]

Depends on the purchase cost between the two if its not much the 70 is well a head, 2 valves per cylinder is very old design, 16 valve is more pf a 2000 era design much more suck and blow but if u keep it a long time its more cost to maintain and service the head after warranty

[TheRealAndy]

The Merc is a good motor but is very heavy for its HP, the Yamaha 50/60 is not the same motor as the 70 (that I know of) the 70 is a motor all on its own, goes pretty well for its light weight.

We have been through a lot of outboards in the 50-70hp range at the yacht club. The worst ever was the Merc 50. I could swear that that it was the exact same block as my 50 Yamaha at the time, had the exact fuel pumps in the same positions tec. But we had ongoing corrosion issues in the leg and the tilt pump and all sorts of issues, none related to the power head.

[scottar]

A lot to consider - least of all the weight between various options as too much is going to mean extra boat speed required to get the hull to perform as intended - all good until it gets rough. We went through a similar situation with my BIL's tinnie years ago - replating from a 25hp 4 stroke to a 40hp 2 stroke on a 395 barra punt style hull. Boat was a pocket rocket and heaps of fun on flat water with the new engine but an utter pig of a thing if it was choppy. We ended up fitting fixed tabs to force the bow down.

As to the change from a 50 to the 70. Only experience I have is with a mates 5 metre Brooker which went from the 50hp 3 cylinder two stoke to a F70 some years ago. Better all round - he loves it.

[stevej]

Saw my hull and the 75 merc done on a hull up in qld hence the request for opinions

I just want a slightly faster boat I won’t go offshore but will cop some dam and bay chop which can be nasty at times
last day out at mulwala i did over 100km under outboard power

some of these inland water ways are vast

[gazza2006au]

We have been through a lot of outboards in the 50-70hp range at the yacht club. The worst ever was the Merc 50. I could swear that that it was the exact same block as my 50 Yamaha at the time, had the exact fuel pumps in the same positions tec. But we had ongoing corrosion issues in the leg and the tilt pump and all sorts of issues, none related to the power head.

The early yamahaand mercury 50hp fours shared the same block

[scottar]

Saw my hull and the 75 merc done on a hull up in qld hence the request for opinions

As a start, add the extra weight that would be involved with the upgrade using buckets of water or some other method to the back of the transom if at all possible or just on the inside if it's not and see what you think paying particular attention to what difference is required in hull speed to get the hull working properly without it's nose in the air and what handling traits may be introduced at various speeds. If possible run it in a bit of chop and see what you think. Faster is great - provided it doesn't end up causing issues with handling or worse still hull damage because you are having to push the hull hard when it's rough. From a personal perspective, a difference of 40 kilos made enough of a handling difference on a 6 metre glass hull for me to notice and then spend money to rectify it.

[stevej]

It’s about 50kg difference
ive moved 30kg of fuel already to the middle of the boat and the other 20 I can remove with a lithium battery

Just going to buy a bigger boat early next year and will sell it if I ever have to downsize to a small block/shed

[Dignity]

Does the boat have a leccy as well and if not will it because there is more weight that you need to consider. A leccy weighs around 14 kg, add another battery even a lithium at around 10kg or AGM around 32 kg, all up front. Adding and moving another 50 kg around will turn it into a rather unmanageable beast.
I know your pain, 2 years wait for a new boat, 2nd hand ones dearer than new ones with low hours but obsolete electronics, and not necessarily set up the way you'd like, the world has gone crazy.

[stevej]

Dignity yes has all that electric front livewell side console and so on
they have a 2.1m beam and can easily float the weight but that width also soaks up horsepower when pushing it through the water
same horsepower on a 1.8m beam and would go 10 Kph faster

anywaywas just an idea that turned out to be wrong move forward and find something more suitable

thinking one of those 5m Barra boats side console 115 -135 long enough for some rod storage lockers and can handle some chop

[gazza2006au]

Get a skeeta boat from the usa i read shipping companies go by cubic volume so u could fit 3 skeeta boats in one container flog 2 off to cover your cost once landed ur laughing

Cost ya about 5k for a hull instead of 60k