http://www.westmarine.com/buy/ce-smith--ce-smith-flush-mount-rod-holder-30-deg--7920010

Ring Surtees Grant, they do extra heavy duty rod holders now and will supply backing plates and all screws etc. I did mine last year, from memory about $300 for 6 sets including ss bolts and nyloc nuts

I would never have thought it , but, Anzor have the follwing heavy Duty ones avaliable. After so many falling apart I ws put onto these a couple of years ago and have never looked back !! !

Espresso wrote: I have an aluminum boat

Nobody has said you shouldn't be using stainless. Get some aluminum ones. As for the backing plate I've purchased some aluminum plate cut to size and also holes in it. 

As always, a whole bunch of good ideas, many thanks guys
Mozz - I nearly just said yes, and really appreciate the offer mate, but I shall try something here in the meantime.
Thanks Joker.
Blackbill - ah yes I remember that place - is great! Oh so nearly went and got them...but will try alternative in meantime, cheers.
Kaveman - cheers I rang them and the heavy duty ones are what I have broken prior to the stainless, but yeah why I didn't ring them straight away to find out I don't know, they are good.
Alexfyssher - yes I use both forward stay and a downrigger, but the flex with the boom out at right angles to the boat is too much, it even bends the gunwhale which I don't like seeing.
Of2fsh - thanks man, gave me the idea to revisit the guy not far from me who's does stainless etc previously (on my Aux.) and make it a super strong holder.
Krow - I have managed to break everything, so have used stainless with the rubber and goo that is supposed to help stop electrolysis.

So since it was persisting down with rain this morning and blowing a gale, it was time to stand outside in it, stare at boat and listen to my nagging brain saying 'do it once and do it right' !!

1. I have ripped the stainless aux bracket, again, (9.9 Aux motor) due to excessive pounding. So that's now off getting more gussets and strengthening. Apparently the manufacturers have never seen someone achieve this destruction before

2. The rod holder will be full re-made, larger topside surface area, a larger surface area plate and angle brackets underneath, all bolted and braced together to the boat.

3. I'll also get the cracked gussets on the engine transom mounts re-welded and strengthened, yet again...this will be the 4th time required to reinforce the engine mount area to stop cracking.

Better to do this stuff now while the weather is so crappy.

It never ceases to amaze me how many products are sold that have no chance or performing in the useage situation. OK so a dredge isn't normal for a rod holder, but all 4 rod holders were destroyed just from my normal use - maybe I'm not normal?