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gcarter
01-12-2013, 11:12 AM
On older Donzi hulls (pre 1994), the stringers are roughly 23.5" +/- distance inside to inside. Sorta like the picture below:

http://www.donzi.net/forums/attachment.php?attachmentid=32671&stc=1&d=1194546320

and don't allow the use of commonly available offshore mounts like these: http://www.hardin-marine.com/p-13273-steel-front-offshore-motor-mount.aspx , which are too wide for the space available.

Does anyone know of a comparably priced product that will fit?

Tidbart
01-12-2013, 01:02 PM
George
The ad says you can cutthem down to 23", if needed.

gcarter
01-12-2013, 05:27 PM
Bob, that's true.
However, my stringers are already at 23" or a little less since I reinforced them, but, if you consider the bolt holes pictured have to bolt to angles bolted to the stringers (I assume), you can't really get bolts through the mounts and the support angles.

MOP
01-12-2013, 06:56 PM
Having had one boat with hard mounts IMO you will regret it, unless you intend doing some hard racing forget it!

bertsboat
01-12-2013, 09:29 PM
http://www.ebay.com/itm/Mercruiser-Offshore-Motor-Mount-Starboard-Port-Center-Mercury-Racing-454-502-/290837456832?pt=Boat_Parts_Accessories_Gear&hash=item43b74367c0&vxp=mtr

maddad
01-12-2013, 11:10 PM
George, it looks like taking the 1 3/8" off each side would remove the existing holes and let you drill new holes where you like.

roadtrip se
01-13-2013, 12:58 AM
George, it looks like taking the 1 3/8" off each side would remove the existing holes and let you drill new holes where you like.

I banged out a long winded response to this and then deleted it. MD is right. You can make a standard single cradle work with a little custom trimming and trail fitting on the ends.

gcarter
01-13-2013, 08:38 AM
Todd, would you mind expanding on this statement?

"With a little custom trimming and trail fitting on the ends"

I understand MD's statement about starting over w/the bolt holes.
What size angles did some of you use to mount the cradle to?

At this point, I'm kicking this around and haven't decided to do it, but the timing is perfect if I'm gonna.

rr1048
01-13-2013, 09:54 AM
I have racing mounts in my 20' Cigarette BBC and the biggest issues i believe would be the initial setup. With the development of affordable replica blocks it would probably make the fitting process a piece of cake. These replica blocks weight in at around 20 Ibs and you can mock up your complete engine if necessary. P-Ayr products can be purchased at Summit Racing and you might want to check these out if fitting becomes a problem.

Brian41
01-13-2013, 10:32 AM
I have done several custom mounts including (2) 22 Classics Donzi's.743787437974380

gcarter
01-13-2013, 11:06 AM
Brian, that's some excellent information, and I'm going to save those pictures.

RR, I think the mock up blocks are an excellent idea.

At this point, I don't need the extra beef of the offshore mounts, but w/500 HP on tap, whoever I might sell the boat to might have plans for even more.
When I was repairing the hull, I reinforced both inside and outside the stringers w/solid glass. I know the inner portion of the bottom (between the stringers) is about 1" thick. W/the closer stringer spacing of the earlier hulls, some of the problems of the later boats aren't evident because the bottom panels (the flat portion of the hull between the keel radius tangent and the stringers) aren't as wide. But other problems exist on the earlier boats, like the stringer cores are flat bottomed so the stress is on a knife edge. Also, the layup is very light since they were only designed for a maximum of about 400 HP. The other main issue was the strake pockets were filled w/putty that didn't quite harden, so the outer strake glass in the area of the engine mounts fractured from fatigue. All of these items are fixed on my boat.

maddad
01-13-2013, 11:14 AM
Brian41, that sitting on top of the stringer set up is important in my opinion.

roadtrip se
01-13-2013, 12:20 PM
Todd, would you mind expanding on this statement?

"With a little custom trimming and trail fitting on the ends"

I understand MD's statement about starting over w/the bolt holes.
What size angles did some of you use to mount the cradle to?

At this point, I'm kicking this around and haven't decided to do it, but the timing is perfect if I'm gonna.

George,

I wasn't trying to be vague about this, but Brian and I went around in circles on this for quite some time, and he had to show
a lot of creativity to make it work. So, I had second thoughts on posting all of this without his consent last night.

I really wanted a cradle on this re-rig, as I knew how they worked in the bigger boats. Having a chance to review some shots
of Mr. X's Ilmor project proved that it could fit in the bilge of a 22. While we didn't follow his recipe exactly, it was enough to
convince us to put the traditonal solid mounts I was going to use aside, and give it a shot.

The top mount stringer pieces are very cool. It makes it very easy to check the system during pre-flight, and I think it provides
more strength than suspending the cradle from the side of the stringers. What you don't see in these shots is the adjustments
that were made for the camber/direction of the stringers and the accessories on the engine. Each side is different and the trial
fitting allowed for the adjustments.

This piece of the Flowerpot re-rig is probably the one I appreciate the most in terms of what Brian put into the fabrication and thought
to make it work. It isn't something I could have done in my garage very easily. I'll dig around and see, if I can find some more
shots of the mount work.

gcarter
01-13-2013, 01:16 PM
I know how to appreciate the time, thought, and effort that went into the fabrication of these pieces.
It really wouldn't be easy to do this on my boat (I'm here at the shop working on it today) w/o a good number of changes.
Some things really need to be planned from the beginning, but it's also good to know a method of doing it.
Also, it'd be fairly easy to do an additional piece spanning the stringers w/o being part of the mount itself.