[Darren Kinvig]

    The question is how far the prop should be under the boat from the face of transom.  Not how far from bottom of hull or how far from strut.  The picture is difficult to take because the underside of the boat is very close to the floor of the shop.  thanks.

 

   Darrren

[Darren Kinvig]

   My question is how far back from the transom face.  Not how far from strut or how far prop from under the hull.  Sorry if the picture is not the greatest. It’s very tight under the boat. The picture shows that the closest prop blade is 2  1/2 inches under the boat from face of transom.

 

 Thanks

 

[Darren Kinvig]

     Ventilation?  is this a condition where air can enter the prop wash/ prop from the end of transom into the prop? Looking at some drive examples where props on some boats appear to be close to the face of the transom, I have seen that the transom has been extended in the area above the prop. Is this a solution to prevent Ventilation?

   Thanks for your advice and knowledge.

[Darren Kinvig]

    Thanks for the pictures Tony.

Unfortunately it is -49F here at the moment. Not able to set the shaft and rudder in/on the boat for a picture.  I hope the text and lines in these pictures will make better sense.

 

 

[Darren Kinvig]

Thanks for everyone spending the time to give feedback to questions I have

I have added some pictures to the text .

First picture shows the gear bracket. It lands in center of the stringer below. There isn’t enough room between the bracket and the stringer to put in the isolator.

Second picture shows the depth at which the stringer would need to be cut out at the top to get the isolator to fit between the bracket and an attachment point. 2″-3″ down from the top. stringer is 7″ deep.
My concern was not wanting to cut into the top of any stringer for fear of jeopardizing strength. I thought it could be boxed and bolted through stringer with aluminum material. lots of labor. has anyone done something like this? opinions….

The third and fourth pictures show how far out from the gear the isolator would need to be moved to be on the outside of the stringer. (11 inches..) I could then bolt an aluminum mounting bracket through the stringer. More conventional. I would need to make new gear brackets. How thick of material and what kind of material would I need in order to span 11 inches from the gear. seems this needs to be pretty heavy material. Steel? thoughts . Thanks

[Darren Kinvig]

1. Prop shaft will be new. has not been ordered/made yet. Starting from Scratch.
2. Prop shaft is aprox. 5’5″ long Need to fit Transmission and get proper length of Prop shaft.
3. Prop shaft diameter is 1.5 inches
4. Prop Diameter is 20″.

I would like to do the final fitting to the shaft.

[Darren Kinvig]

Thanks for the reply. I am starting with nothing but the shaft tube/log in the boat. The strut will need to be replaced. The prop shaft that came with the boat was an 1 3/8 . I will go to an 1 1/2 shaft diameter. I was hoping not to replace the shaft log. My first time doing an inboard/v drive set up. So the extra clearance sounds like a good idea. Your shaft was so miss aligned that it was wearing at the shaft log/tube itself. Allot to learn. Thanks again for your reply. Some helpful information in there.

[Darren Kinvig]

Thanks Tony
Is it possible for you to modify or supply an X tank that will work in my application? If I could get some of those fittings and water line I could do it myself. Your explanations to these questions sure helps to clarify allot of questions that come up in the planning stages. It can be difficult to understand where to start and what parameters to plan within. there is no written installation manual pertaining to each particular engine/ trans combination Some installation manuals are written in a way that restrict installation options. thanks again

[Darren Kinvig]

Thanks Tony.
To be clear you are saying It is okay to tilt the Cummins engine “Nose down” in order to get the proper angle to get clearance for prop? That is what needs to be done in this case. When the boat is running onto step the rear of the boat will drop more, resulting in more nose down attitude of the engine. The Issue I imagine could arise in a nose down attitude:
Air would be trapped in the cooling system at the opposite end of the expansion tank on the engine. This can be dealt with proper coolant tank venting? How costly and complex is this?
You say the oil pan angle does not care in this case. When the boat is trying to get on step at what point, or at what angle does the oil pan angle matter. Oil pan angle to me means at what point does the oil pick-up have no oil to pick up due to oil running to opposite end of oil pan.

Thanks again Tony.

[Darren Kinvig]

Wow. I would sure like to ask you some questions. I am doing the same thing to a 28′ flybridge Single diesel tho. I’ve done fiberglass work, painting, and lots of stern drive installations. Never a inboard – V drive set up. Going from a Cat. 3208 borg warner to a 6bta Cummins with a ZF combination. If you have some pictures of what you did it would be great if you could post some. Sounds like it was well worth your time and effort.

[Darren Kinvig]

The PDF drawing shows the original Prop shaft angle and the theoretical prop shaft angle using the cummins/ZF repower. The front of the Cummins engine is set in the same location as the front of the original Cat 3208.
The drawing shows the engine mounted at zero Degrees. At zero degrees I lose 3 inches between prop shaft center and bottom of hull due to transmission angle differences. If the front of the cummins is raised higher I would lose more space. My goal was to continue to run a 20″ prop.
Is moving the Cummins toward the bow of the boat an option to gain space between prop shaft and bottom of hull? Where does a person Start?

[Darren Kinvig]

Thanks for the reply. I have spent countless hours on your website. it is the most helpful/informative collection of material I have run across on the internet. The very basic part of this issue is the fact that if the nose of the engine goes up facing the stern of the boat the shaft also goes up toward the bottom of the hull. I lose the space between the shaft and the bottom of the hull. As long as the recommended “installation angle” is not too rigid I feel more confident I can make a 12 degree down angle V-drive fit and have the dia. prop. I want. Scale drawings are not my forte’ but will do my best. I realize it needs to be down prior to starting the re-power.

[Darren Kinvig]

Hi. I have read in many forums different opinions about engine oil for the 6bta engine. To be honest it get’s confusing because of everyone’s opinions. I understand that some oils are easier found in some locations than others. Price may be another factor. I can look up recommended specs and find various oils that will match the specs. What oil and viscosity is commonly used in the 6bta engine? synthetic or Dino oils? What are others using, why and their experiences with various oils? Should you use a break in oil on a rebuild? You would think that oil is oil and it shouldn’t matter a whole lot until your engine is in an marine environment. maybe someone (tony) can simply say. Use Royal purple 15w40, or, or ???

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