several people and boatyards have recommended international interspeed ultra antifoul for the boat but i have read that you cant use this on aliminium, i think my outdrives are ali as are my trim tabs or am i thinking S**T?
Yes you need a special outdrive paint, all outdrives are ali, there is copper (i think ) in hull antifouls and the effect is like two dissimilar metals in a battery, so the outdrive starts to get eaten away. International do an outdrive antifoul but the colour range is limited, which is why mine is always battleship grey.
But to answer your first question - outdrives almost certainly al-YOU-minium and tabs stainless or al-YOU-minium = not Interspeed Ultra unless you can assure no breaks ever in the primer (ha ha re tabs)
You need an MPX paint for your drives and tabs, can get it to brush on or spray on. There is a new one out which is very good but the name escapes me at the mo.
Make sure you leave an inch gap of antifoul around the transom shield when painting.
Ive just antifouled my boat, used "Seajet" antifoul 30 quid a tin and brilliant. For the outdrives use arosol spray on paint by VC tar, its the correct colour and the spray gets into all the awkward parts dead easy. If existing paint is poor use the primer first. i think its called "prop O derv."
Nothing will grow or stick to your drives when this products on.
I'm using "seajet shogun" I think it's called this year in the med, just bought 40 litres for about 550 Euros in 20 litre drums, reccomended by my brother, he had it on one of his boats up in morcambe bay, where the foulilng is quite bad, no problems. I'll need it all this year, scraping a bit of the old off here and there, where it's a bit thick and crumbly!