My dad recently upgraded his Mercury 15hp 2 stroke (mid 1990's model) to a new Mercury 15hp 2 stroke.

He is very disappointed with the new Mercury, seems to run a lot rougher than the old. I believe the old was made in USA and the new in China?

He wishes he had got the old one fixed instead.

Can't comment on the Yamaha but have heard good things about them.

Stick with the yammy mate you get what you pay for I've got the 03 model like yours touch wood it hasn't let me down my old man got a new 50 2 stroke merc and he's had it back in the shop a couple of times with fuel issues and a few other little problems 

 What is not mentioned in this arguement is that yamaha does not maintain a full spare parts inventry for many of their models in Australia. You can wait a long time to obtain critical spare parts for many models and this is not an isolated issue. Mercury marine has the largest service network on Australia and the largest spare parts inventry. I am awaare of 6-12 months wait times for yamaha parts, there are many disgruntled Yammie owners with complaints re warranty issues with yamaha . Mercury stand by their products and have an enviable reputation in maintaining customer support. I do not work for mercury and do not have a vested interest in this company. What i do have is 40 years of commercial fishing using thier products from twin cylinders up to the 6 cylinder models. I also have the same time with my collegues using the competition and have recall of issues experienced by fellow fishermen. 

Mercs 50:1 oil ratio compared to yami 100:1.

I have a 15 merc yank built at present only because of the gear shift on the throttle is great for trolling but hate the fumes. had yamis and loved the cleaner running but side throttle was a pain. Been looking at Suzuki 4 stroke as the lightest on the market at present and reasonably priced.

ive just recently re powered my 4m centre console with a new 30hp mercury and it absolutely pisses over the 30 yammy i had on it. Runs awesome and beat everyone hands down for price, I was keen on the Suzuki but found that the Mercury was only 3kg heavier and the new yammy in the same size was a hole 20kg heavier than both. Unfortunately the main thing that took me away from the Suzuki is the owner of the dealership in my area is a complete fuktard 

It’s a no brainer go the yammy for reliability and resale 

 Years ago when we were looking for a new dingy motor. It was alot cheaper to purchase (drive all that way) in mandurah for a 15 hp Yamaha though our local suzuki dealer matched the price . No way i was driving down for thr yammy now! That suzuki didnt miss a beat all around oz that year and ran on fek all. Just saying, ask the question to price match for what you want or at least something better. The answer may be a yes!

I would stick to yammy. Easy to service. Proven outboards .

 Thanks everyone it does seem that most are saying stick to Yamaha. I'm just spewing I didn't buy one a few months ago I could have got it a lot cheaper. The only place I can find one now is in Bunbury and I kinda feel as though has jacked his price up because he knows nobody else has any and he has 4. Im also considering fixing my old one in the future. If and when it stops and leaving the dealer in Bunbury with his over priced motor maybe just ring him the day before the cut off date and see if he wants to drop his price. 

 Id just stick with the 30 you have now, dont think theres a hell of a lot of difference between the 03 and now anyway. 

Ive got a 2013 yamaha 30 thats done well over 1000hrs without missing a beat, swapped to a 50hp merc and while its a much nicer engine (quieter, better on fuel, less smoke at lower revs) it kept annoying me with small issues that has made me swap back to the trusty yamaha. 

have had both mercs and yammys
from small 4.5hp up to 90hp , had mercs from the late 70s to early 90s , then swapped to johnos and envinrudes ,over 8 years or so , got my first yammy in 2000 , it never missed a beat and did over 900 hours pretty much trouble free , never had an issue with spare parts or services etc

bought another new yammy [same size ] in 2016 to replace the old one , its been the same reliable as and never missed a beat over the last 3 years

the mercs we have had where good motors generally , but did give more issues than any yammmy iv ever had , admittedly that was back then , but yammys have proven ime to be great and my preffered go to motor first up any time

worth mentioning a lot of problems with any motor can be eliminated by simply flushing with clean fresh water every time and quality oils and maintenaince throughout there life ..

 I agree hezzy I Always do a good wash and flush I have also with this boat unclipped the fuel line and run engine till it stalls to try and not leave fuel behind. 

 I work in PNG and along the coast there is thousands of Pangas or Banana boats, whatever you want to call them and they all have the 2 stroke Yammys from 55 to 85 hp. They pre mix there fuel. The motors never get flushed and minimal maintenance    

Yamaha all the way,but if spending the extra is a stretch all that matters is your on the water!

I went to  30hp Mercury in 2012. 

It was about $400 cheaper. Parts are easier to get plus the 5 year warranty won me over. 

I have not had any trouble with it what so ever.

Very happy with it

 Cannot fault this motor. I think with most 2 stroke outboards, if you service them annually and use good fuel and oil (Yamlube for mine) then they should remain bulletproof. Ive also previously had Tohatsu's and they are another bulletproof engine.  

check this out lol

https://www.facebook.com/whitiangler/videos/vb.297061407164283/1282210188614699/?type=2&theater

Yammy good . Don’t think there quiet that good though.

 Just swapped over from a 50 2-stroke (Merc '99) to new yam 60 4-stroke. The mercury was fantastic, acted just like a 2-stroke should and still worked perfectly. I only swapped over because it was 20 years old and I was heading to Lancelin over the June long weekend to fish 20 mile offshore and got paranoid that this would be the.. ya know ... time. Wanted a new Merc (done me so well), did the ring around and even though the Merc would've been marginally cheaper,  Chivers was the only one to offer me the trade-in which squared out any cost difference and saved me the effort. 

Obvs the new Yamaha got me back and forth on my 20 mile effort with absolutely no dramas (but surely youd expect that) I'm just glad to see there's a lot of good comments about the yam. 

PS only got one baldy to take home for my efforts. ☹️ And one Port Jackson to throw back (which I was convinced was a Dhu when pulling it up)

 The old two strokes in that size range were pretty bullet proof, and I doubt there’s been any meaningful updates in the past 10-15 years.

If you get a new Yammie you are effectively just buying a complete spare motor for some day in the future.  If you get the Mercury you aren’t even getting that.

Unless you just really want a new engine...

PS - better off to stock up on a few likely spares.

 I am probably leaning towards what you are saying I'm definitely going to stick with Yamaha at the start I was seriously considering the mercury but as people have said the Yamaha is pretty well bullet proof. Do you think the spares will get that hard to get? I would have thought that there is still a good market for them advantage is though if you have the parts you don't need to wait for them. 

On my new yammy . Well used :). Done sevicing from new. Only thing I stuffed up was water pump case ( my fault). Getting up there in hrs no dought something will give . Prior to my four stroke yammy I had a 90 hp two stroke yammy. Massive hrs . Never let me down. Motors are motors if you look after them they last . I know 2 people who done under 100 hrs on yammy . They blew up . Oil pick up stuffed up. Pick what you like young fella .