I just mounted a new DF150 on the back of my Chivers and set the anti-cavitation plate 1 hole (0.75 inches) above the bottom of the hull.

I think the starting point is to have it set level with the bottom, but can be raised depending on the intended use & likely top speed of your boat.

I think the cavitation plate should be level with the bottom of the hull/keel. Maybe a squidgen lower.

If you have it too low it just creates more drag meaning less speed amd more fuel used. I think...lol

The cavitation plate should be just above the line of the bottom of the hull and if you are after high speed even higher.To slow a boat down drop it down.

i would start with the cav plate being level with the bottom of the hull , disregard the keel if fitted but i would then look at lifting the motor so the cav plate is is slightly higher than the bottom of the hull,  then get your boat on the water and see how see goes at reasonable speed,, you should have no cavitation and you should be able to see the majority of the cav plate exposed whilst running, to much plte or cavitation the motor rquires to be dropped or if the plate is covered or throwing water up means the motor requires to be lifted,

I am going through the same process now with my 150 Merc. I spoke with the guy from Oz prop specialist on the Gold coast and he said for every 6 inches the motor is back from the transom, the cav plate should be 1 inch obove the bottom of the hull. Mine is on a pod. 3 feet off the transom but as it now on the max high seting. it is 4 1/2 inches above. It will also increse the  rpm.

i spend over a year fitting engines in a dealership and what has been said here is true. you want to have the cav plate at least level with the transom. if in doubt go higher, not lower. the rule for pod i thought was for every foot back from the transom you raise the engine height 1 inch, but it may be 6 inches. once you have hung the motor trim it up and stand back a bit to check the height. if yoy have drilled your transom holes right you shouldnt have to make new holes as you suggest but just lift the motor up a hole. the hooks as you are talking about dont realy mean a lot. you dont have to rest the engine on them as its the bolts that holt the engine on, not the hooks. have a look at most boats and you will find that they dont rest on the hooks. you should be able to find a template on the net somewhere about where you put the holes in your transom. it sounds like you have a new boat/engine so if thats the case just make sure you get the centreline of the boat when you measure where to put your holes. dont measure the centre from the sides of the transom but the sides/rails of your boat. their is no garentee the transom is in the centre. i would think that where you bought the engine from would have a jig for the holes. failing that the etecs used to come with a paper template somwhere in the paperwork for the holes... i think.

other things to think about or remember...

unwind and straighten all the control cables before you fit them for smoother shifting.

apply grease or loctite to engine mounting bolts to keep the salt out so you can undo them in 10 years time. if yoy are putting silicon around your bolts(a good idea below the water line) put the grease on the bolts first as silicon on the s/steel bolts can gall up and sieze the nut and bolt beore it gets tightned.

pull out each small screw on the control box 1 at a time, put grease on it and tightn back up. keeps salt out and allows eaiser maintenance in the future.

do the same with the side cowlings on the engine. lots of grease.

dont fill the oil bottle with oil untill you have checked the low oil level alarm works.

the only other thing is adjusting the control cables. the throttle cable needs to put the throttle lever(on the engine) all the way back on the stop at neutral.

the gear is a bit more tricky.when the control box throttle lever is about 3/4 throttle forward, you want to adjust the gear cable black plastic adjuster thing on the engine side of the control cable untill the metal gear lever has a bit of movement in it. then in reverse it sould also have a bit of slack. from memory i think the black plastic adjuster is 3 turns back from all the way to the control box as a starting point. this bit is crucal to get right for smooth shifting and reduce wear on the box. if it does not shift smooth  it is propably this. dont forget to put some greae on the control cable adjusters to. oh and obviously dont try to put it in gear without lining up the dog clutch, ie spinning the prop shaft.

thats about it realy. but as i said i used to fit these to boats so if you want any help just send us a message.

Okay this information can be true in regards to pod and prop height  as stated dont just put the engine up as high as you can small incraments and test run and keep going .This engine cavplate to hull is imprtant it is how we achieve maximum speed and efficiency it all so pays to test props as all props have different features bow lift,stern lift and some just to push heavy loads .It is all so quite easy to disturb your LCG longitudial centre of gravity by doing these procedures so fuel placement batteries storing gear this is not just a afternoon job it is time and more often than not exspense. 

Another tip if the fan tale is rather large each side of the cavplate then your motor is too deep.A well set up boat will not need a hydrofoil on the cave plate or the use of trim tabs to get on the plane  if it does it is either under powered or set up is wrong.Once the set up is achieved it is worth the time great fuel economy and reasonable performance these boats at the end of the day are fishing rigs not hi-po boats so be realistic you are not going to get the whole package go for recommended revs and fuel economy . Happy engine testing

 Thanks for the advice guys really helped,

Went out sunday arvo just outta maylands, pretty happy with it, didnt really open it up fully, but was pretty happy with it, I'm a little concerned about if we open it right up that we will get too much bow lift on it and flip it over, what options do we have? maybe a wing thing onto the cav plate? Would that be worth it?

Cheers,

Josh

How big is the boat you fitted the motor to? Anything under 4.5 metres should be ok as long as you keep the leg trimmed right in when you give it some stick. Once it comes up over the hump and sits on the plane you can back the revs off a bit to find a comfortable speed you want to travel at.

Hey

We put the motor on a late 60's dehavilland 14 foot alloy boat, took it out for a real run today, and rekon that I had it trimmed incorectly with the leg too much in the water, as it didnt really get up and go like we expected, although still heaps above the old 35 that came off it, I think there is still some fine tuning to go.

Josh