Im looking at getting a tractor to beach launch and after a bit of advice.

Power wise will be ok, but watch the dizzy/coil does not wet, if brake shoes get wet, they will not work, could always fill rear tyres with water

You have a nice expensive boat dont buy a cheap old tractor specially if you are driving down a slope. Spend a bit more and get a diesel with wet brakes and power steering. You wont regret it and will feel far more safer.

For around the same money you should consider a cheap reliable 4x4 (L/rover, Pajero, Bighorn or similar) and leave it at the beach. Starts every time, road legal, trailer lights, better brakes, secure, warm & dry...

The thing I don't like about the 4x4 option is it will have to have wof and rego at normal car prices. And that it will be backed into the tide possibly further than a tractor. Tractor won't need a wof as it will be operated under 30kmph and rego is a lot cheaper so it will be road legal and easier to keep road legal than an old 4x4 that gets dunked in salt.
You can get a tidy Fergus for around 2000 but a tidy diesel your looking at 3 times that. Is it really worth the extra? It isn't overly steap the hill and if engine braking works better that should be no problem. But if a diesel db or international is that much better with wet brakes then I'd would look at saving more

All good advice. The more you spend ~ the better result. I am on my second diesel tractor (with hydrostatic gears) and would not go past another in the future. Give Eric from Gatmans in Silverdale a ring. Tell him "Wayne" put you in touch. Great guy ~ great advice. Not pushy at all. He traded my first tractor for what I paid for it two years ago. Sure... you will spend a little more from a dealer, but they are handy for repairs and advice. Warranty is good also.

So why do you question using a tractor on castor bay beach?
Is it just the traffic issue? I understand being ticketed etc for not having rego etc but I'm fully aware and prepared to register the tractor and having working lights and the brakes will be maintained it won't have a wof as it is not required by law to have but it will be to wof standard. I'm not going to buy some old cheap hunk of **** that doesn't do anything right. That is why I'm asking here for what tractor it will be best and if there is a meaningful difference to spend 3x as much for a diesel tractor for a 3-400m drive to the beach.

For those saying about 4x4 how good are they if all 4 wheels are in the water at all? And is there more to go wrong when it's getting wet and still needs a wof compared to a tractor?

What are 4x4s like on flat shallow beaches?

I am not sure about WOF not being needed. This is quite an arguable point. The rule you are applyng to refers to farm machinery. It is questionable whether a tractor in Castor Bay is a farm vehicle. I would suggest that different officers would see it different ways. Regardless , your brakes would need to be 100% all of the time. Especially where you will be operating next to a kids playground.
I still stick to what I alluded to before. I don't think a tractor is good form on one of The Shore's busiest roads & the fact that you leave the beach on a blind corner. A tractor is not the speediest machines off the mark. I personally think that , used regularly in that location , you will be an accident waiting to happen.
I use a 4x4 on the same ramp (also Milford Marina) and have had no troubles at all.
I would not even consider a tractor in your situation.
Anyway .. Not my concern ... Just my opinion.
Back to your original question ~ give Eric a call from Gatmans. I think he will tell you that there hasn't been a Fergie made, that can stop in the prescribed distance at the prescribe speed. Possibly , one of the more modern (diesels?) will

Ya dammed if ya do and dammed if ya don't. I kin tell you it's character building being pushed down a greasy sealed slight sloping Rd (TBC)by a 8mtr trailer boat with the front wheels bouncing over the road surface. ....