Ranger Tug 25 with 110 HP Yanmar

[dclagett]

I am looking for information on classic Ranger Tug 25 with Yanmar 110 HP engines. The information I need is what is the ratio of the reverse gear and the prop specifications for the Yanmar installation. I have asked the Ranget Tug factory and I was told they do not keep information that far back. I am in the process of repowering an RT25SC and going from a Volvo Penta D3-150 hp to a new Yanmar 4JH110. I am not concerned about speed and willing to loose a few knots for a more maintainable engine installation and a manufacture that does not treat product information as super secret. The new Yanmar bolts directly to my new ZF45A reverse gear and fits in the engine compartment with room to maintanin the engine. The installation is going very well, however I am trying to nail down the prop size without going thru several costly iterations.

Thanks, Dick

 

[BB marine]

This is not first hand info. This is information that I know of. The older Yanmar package had a Kanzaki reverse KMH4A I believe the ratio's were basically a 2 to 1 and a 2.4 to 1. I would assume the reverse gear used was a 2 to 1. The Tugnuts forum Ranger Technical bulletin section has prop specifications for the R25 classic with a 110 yanmar. Acme part # 1118 17x17 3 blade .125 cup. Using this prop, with what I would assume a taller ratio than the ratio you have would indicate this prop may be to big for your application. The best way that I would go about propping your boat with the new engine is go to your log books and get the WOT max speed numbers matched to the RPM the engine was turning. Write theses numbers down
along with the D3 Volvo Hp (150) and the gear ratio of the reverse gear. Write the Prop specifications down that you were using when you recorded your performance numbers. Give this to a reputable prop shop that knows how to spec props. If this is not available to you in your area. Call Acme Props give them your information and they will be able to tell you what prop size will put you in the proper RPM range for the 110 hp Yanmar. This prop will be based on the performance that you experienced with the D3 engine. So if you were over propped before they may lighten the load more so that you are not over propped now.

The 17 X 17 .125 cup is slightly more prop than I had on the C26 with a 220 hp D3. S0 I think the factory prop used back then on the R25 would be way to tall with the gear you have. If it were me I would be going with the proper sized prop with 4 blades instead of three blades as you customize the power in your R25.

 

[dclagett]

Brian,

Thanks for the information. The prop I have on the boat now is 17" diameter, 14" pitch and 105 cup. I believe it was properly sized for my D3-150 since the engine was able to reach 3000 rpm at full throttle and with the boat loaded. I do have a prop shop in Easton, MD near me that has an excellent reputation in the area. The yard that is doing the work on my boat is working with that shop for either adjusting my current prop or obtaining a new prop. I have given the performance numbers to the yard & prop shop for the D3 performance. The prop shop wants one additional performance number and that is with the Yanmar installed running with my current prop. So that is the current plan. Your suggestion for going with a 4 blade prop I am considering. My understanding is that it gives better low and cruise efficiency, but lower top end performance. Since I am not worred about speed the 4 blade may give better performance at the low to medium speeds and save some fuel in the way I operate the boat.

Thanks again... Dick

 

[BB marine]

The four blade has more surface area which usually reduces slip. Prop slip percentages are higher at lower speeds. Reduce prop slip = better economy and performance.