Hi Phil,

Perhaps this picture will help explain what I am talking about.

On a standard lower, there is an Anti-Ventilation plate. This plate must go away on a "shorty" to make room for the prop (or you would be limited to very small diameter props). The shorty manufacturers do give you a plate to mount on the spray plate of on the driveshaft housing, extending it over the prop, and making it the defacto anti-ventilation plate (it now sits above the prop and keeps the prop from sucking air down from the surface, or ventilating, when getting on plane).

On a standard Bravo lower, there are exhaust ports between these two plates. When you want to divert the exhaust through the prop, the exhaust exits out of these ports above the anti-ventilation plate as well as through the prop. Since that plate does not exist on a shortened lower, if those exhaust ports were there, it would just dump the exhaust on the prop and ventilate it and you go nowhere. At least not off plane. So on shortened lowers, those ports are not there (even though there are usually indentions in the casting for them). That leaves you putting all the diverted exhaust through the prop, which will probably not flow enough.

Now the good news is that a couple of us were doing some work on water rise after the transom and at normal planning speeds the 7 inch setback of the ITS will not appreciably affect prop shaft depth. It is therefore doubtful you will have any more drag than you do now with the standard gimbal. Even my drive at 8 inches deep keeps the spray plate out of the water at planning speeds and I bet the 25OL is more like 6 1/2 inches deep so that is not an issue.

Just think about it before you spend big bucks on a shortened lower unless you decide to deep six the diverted exhaust capability.

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Sure does thanks for the info.. Didn't realize there was exhaust ports between the 2 and I don't know my prop depth because I can't put the drive all the way down as it sits in the garage so I didn't measure it.. the boat sits pretty low on my trailer. When I get the drive back on I'll take measurements and let everyone know what the propshaft depth is. That also is good to hear that the 7" setback shouldn't cause to much more drag. Guess we should have some real world numbers in 2 weeks that I can share.

When I added my imco box I lost the ability to use the Y pipe, so all exhaust is straight out the transom. I had the quick and quiet II, no switch to divert , so the exhaust had two ways to flow at all times. I thought this would hurt me especially at first when I was still running the corsa muffled tips. But it didn't seem to make much of a difference from the prior year with the y pipe to only through transom with the corsa muffler tips then finally to the Dana marine tips I have now. I think the 4" diameter of the through transom is enough for 4 cylinders. I suppose with the captions call performance may be affected without the ports that are lost with the shorty lower when using the captains call at WOT runs.

Got a little more work done yesterday got the hydraulic lines mocked up so I can take it to a hose shop and have custom braided lines made. Started polishing the diamond plate.. got the front and one side done, and found an issue with the water line. There is a piece of plastic wedged in it so next week I get the joy of removing it without cutting the water line.

Starboard line:


Port Line:


They actually will be the same

Back of the ITS:


Closeup of the waterline:

Hopefully you can just pull that little puppy out of there. If not, the helmet end of that water hose is easy to remove. Be glad it stuck there and not up at the transom.

Good luck and looking real good there!

Good find on the piece of plastic! Can you get a little drywall saw in there and cut it in half and then pull each piece out?

I hope so.. It's too deep for a side snips I can reach it with a needle nose pliers. Here is a link to 2 videos. First one is trying to get the weight distributed right so it'd lift the motor over the front motor mount studs enough that we could slide the coupler out. The second one is coming the rest of the way out. Only thing we forgot is to unhook the oil drain line from the plug.. The most nerve racking racking part of the whole ordeal was having 1200lbs. of motor hanging over my head.

Got the hydraulic lines bent and ends put on today.. got the trim ram bushing. The input shaft is on its way and should be here by Wednesday so the light is at the end of the tunnel... still need something to put in the rim to plug the hole where the depth gauge use to be.. open for suggestions....

Also guys if you are using Photobucket (or maybe even the paid site) hit the source button(last one on the top of the screen) before you paste the link or else the picture won't show up

Finally got some free time to work on my other project and got some paint on the cellphone holder:

Test fit in the boat.. still not quite sure how I'm gonna attach it and I still need to coat the inside with plasti-dip:



This is what I pulled out of the waterline.. It looks like the old plug:






Pic of the Transom with the alignment tool in:



Hydraulic lines installed:







And finally the input shaft arrived last night while I was working on the boat. You can see how much smaller a Bravo I input shaft to the gears are compared to a Bravo I XR.