Prop size

[richard collette]

Thought I would look into a more efficient prop as I plan to do the LOOP and still have the original props on my 1971 43DC and they are getting thin. Have had many theories passed by but thought I would ask the experts and perhaps someone who put a different size on their 43. The original 671's and current props are 24x26x1.75.
Can anyone out there help me? Thanks

 

[saltshaker]

Your best bet is to take your current wheels to a prop shop, give them speed at cruise and wot. They need to know what max rpm is fully loaded. Comparing to other similar boats will get you in the ballpark but the weight of these boats can vary greatly.

 

[eze2bme]

The original props on my 1979 43DC with 310 hp 6-71 naturals are 24x24.

 

[Canuck Dennis]

24x25 1979 43 dc with FB 310 HP x2

 

[Walter P]

Keep in mind that the prop specs also need to include the gear ratio. I had 2 43's, a 1973 w. 6-71 J&T's. which spun 24 x 24 x3/4 Nibrals. The other was a 1980 model with 6-71 TI's which had...ready for this........24 x 23 x3/4, an inch less pitch and much more HP. The difference was the gear ratios. The 73 boat had (long time ago, but I think 1.97 to 1 Twin Disc). The 1980 boat had Capital gears @ 1.5 to 1. By the way these were factory spec props when new. Obviouisly the 1980 boat props spun faster at any given RPM, but with more powerful engines it worked out.

Walt

 

[eze2bme]

Walt is correct. My 1979 has Twin Disc MG506 1.97:1 trannys

 

[ron6785]

The original props on my 1979 43DC with 310 hp 6-71 naturals are 24x24.

The 8/71 naturals are 313-318 HP how is it there is so little difference between the 6 and 8/71's ??

 

[jim rosenthal]

It might be a matter of year of make, and injector size and CR. All of these engines came in various states of tune, and different dealers would ask for different specs. I don't know if Hatteras bought the engines directly from GM, but Hatteras may have had something to say about power ratings and which gears were going in them as well.

 

[TROUBLE]

My 1972 43 dc has 8-53 naturals and 24x24 wheels

Art

 

[Walter P]

Ron,

I have also wondered about the HP ratings between 6/71 and 8/71. "Standard" offerings on some 6/71 engines (TIB's) were 485 HP. Very few 8's went that high. Have no idea what the thinking of the engineers was but I also believe that the average life span of equal or close HP on both engines is greatly in favor of the 8's. Hatteras contracted with two primary marinizers.. Johnson and Towers and Covington. Those suppliers were given the specifications regarding their needs by Hatteras engineering and the engines were supplied. To the best of my knowledge, Hatteras did not buy directly from GM (Detroit Diesel Allison division). Possibly because not all specs called for Allison transmissions. Many, perhaps most of our boats came with Twin Disc or Capital gears. Besides at that time basic engine packages were done by companies that specialized in marinizing. Also remember Grey Marine?

Walt

Walt