Arneson conversion on 21' ski boat
 

I posted this incorrectly under general boating area, until I noticed there was specific drive forum

https://photos.google.com/share/AF1Q...dnU2ZGZWtvR0h3
Fantastic site, I always read lots of good tech stuff, and nice to see so many beautiful boats

Have finally started on my converting ski boat over to arneson 1720 bronze direct drive to 21 ft ski boat
originally this boat was run with 250hp outboard, and then the chap I purchased boat from had hacked out the transom for inboard leg setup
after closer inspection lower transom was rotten and back 700mm of stringers
so bit the bullet, and cut out the lower transom. It needed to be modified for the arneson, although was looking to run a wedge to straighten the transom angle thinking transom was solid and didnt need any work
so where are we at present
the transom is now modified, well all the hard work of cutting, grinding, fibreglassing, and reworking, it needs finishing
I used vinyl ester and 600grm (2oz) CSM, 17oz biaxle, and 25oz biaxle fabric, and ended up with 48oz on inner transom, and 67oz on outer transom, laminated onto to 3 layers of laminated marine ply, giving total thickness of 70-75mm
so with some luck it should be stronger enough

Now turning the attention to repairing stringers

as far as mechanics, i will be running the arneson 1720 bronze drive, using RH 19 spline prop, not sure of final prop, have managed to accumulated 6 of them over last few years ranging from 14.5-17.5" dia and 18-23" pitch
have managed to purchase casale, and Hallcraft Z-drive with a range of gears from 1:1, 10%, 22%, 28%, 33%, 38% which should give me plenty of scope to tune setup
the Z-drive will be mated to crash gearbox for F/N/R
19" K-planes
mating to turbo 502 ci or Nat Aspirated 565 ci

I need some help of 2 questions:

1. TRANSOM ANGLE:
the lower angle now is 3-4 degrees, upper transom angle is approx. 16 degrees
DO I NEED TO RUN A WEDGE WHEN ARNESON IS BOLTING UP TO INCREASE LOWER TRANSOM ANGLE TO 6 DEGREES

2. HYDRAULIC STEERING PUMP:
I'M NEEDING CHAR LYNN HYDRAULIC STEERING, I'M AWARE ON THE LARGER ARNESON ASD 8-10 THEY ARE USING LARGER HYDRAULIC CYLINDER FOR STEERING AND USE MODEL CHAR LYNN 211-1010-002 WHICH GIVE APPROX 9.4CI
HOWEVER WHAT CHAR LYNN MODEL IS USED ON SMALLER ASD 6, WHICH i ASSUMING HAVE SIMILAR HYDRAULIC STEERING CYLINDER TO WHAT i HAVE ON 1720 DRIVE, WHICH LOOKS TO BE 2.0: ID X 10' LONG, WITH 1' RAM
Therefore was thinking that would need char lynn 211-1007-003 which outs out 4.5 ci

i POSTED A FEW PICTURES OF THE BOAT WHICH IS WORK IN PROGRESS

any help would be much appreciated

Cool stuff .

Australian?

Ok..... .. .. .. .


Your 1720 has a 6 or 7 degree angle cast into it. Your mounting surface of the transom where the socket housing is to be mounted needs to be roughly 12-13 degrees in order to enable the drive to be mounted with the ball end down.

I'd hope your " Hallcraft Z-drive" will fit in there and it's short. Also, I don't know how much HP and RPM your going to be making with your engine and that will determine the underdrive requirement. At least 33% under is where I would start.

Propellers.. 16" or greater, but try all of them as you never know unless you try. 23" pitch with the 33% underdrive and your engines RPM will equate the speed..

The 1007 helm will work fine with your setup. Your going to need a good p.s. pump on the engine!!!

Rik
Thanks for stepping in
- the transom is roungh finished so can add some more angle in lower section without too much problem
- I have a hallcraft and casale Z drive but have more selection of gears for the hallcraft
- Im not sure of the hp however with turbos should be able to dial it in around 600hp +/-, happy to run to 6000rpm now and then, as need it to be safe as well
- Im assuming if we keep the torque sensible at lower rpm when taking off, the arneson will handle the power at top end, although seems we are at maximum torque for the drive, however they look strong.
- thanks for confirming the helm, I was going to use a Saginaw chev/mercuiser pump, although I havent check out yet what the flow on this would be
- my plan is to have this running by next summer here in Australia, so we will see how we get on. Just finishing the last stringer in boat which is 11"x2.2" wide
so then on with the fit out
thanks

Rik

The 1/2" UNF/UNC mounting studs which are used to hold the Arneson 1720/or ASD6 on transom are 316 stainless steel or some other Grade 8.8 tensile stud.
My transom is thicker and need to arrange for some longer studs
thanks Brett

They were just threaded S.S. rod I believe. Not hard to make

Grade 8 will rust away over time.

Rik
picked up 1/2" UNC x 36" long this morning
cheers
Brett