I have a 35hp GD SD that I just modded up to a 70hp. I currently have the stock 12-pitch, three-blade prop on it. However, it has been brought to my attention by a few different people that I should go with a different prop. I spoke with the guys at Hopkins who recommended a 14-pitch, two-blade tulip prop. Then the guy that modded my motor out for me recommened that I stay with the current prop. I have a Beavetail 1860 that I use in a wide variety of situations (ie. big water rivers with fast currents to back water mud flats). What does everyone else think/recommend? Any advice would be much appreciated.

Nice man, i found that the 2 blade tulip vibrated too much for me but ive also heard of it workin fine for other people. Have you considered changing pulleys to make the prop turn faster? how many rpm's you gettin?

Im not a 100% sure but i would think that the pulleys mudbuddy makes could work on the GD

Speaking from a lot more experience with outboards rather than mm's....

But also having and currently running mud motors....

And knowing that there are a lot more guys on here that know a lot more than I do...

You don't mention what rpm's you are currently turning. Does that mean you have not run the boat with the new mod's yet?

My main experinece with props and switching them up comes from outboards and I know in that case, you can just never tell. You have to try them out. You have to match your goal (power or speed or middle of the road) with boat and motor, and then try a few that seem that they can work. I can tell you that the same prop on the same motor will perform completely different on two very similiar boats. I have even tried props that 'everyone' said would be better on my boat and motor only to find out it wasn't.

If you have not run anything yet, I would run the stock FIRST, and then adjust based on what you find out from that. Turning too many RPM's? Not enough hole shot? not enough speed ? whatever you may want....

Then post up your results -what prop you tried, what rpm's, what hole shot, what speeds,-both with no load and with load-different conditions as you would normally use the boat, and then what you want it to do differently from what it is doing.

Then my guess there are a number of fellows on here who can point you in the right direction... you just got to give them enough info to help you...

12.25 Big Blade Thats what i run I have ran that Hopkins and was disappointed it was slower and did not perform well in the mud

I ran a Stage 3 GDSD for 3 years on a 18x60 PD hull and did ALOT of prop testing. I found the factory 3 blade GD prop did the best all around. Had several props built by Hopkins and none did as good FOR ME. The 14 pitch Hopkins tulip would not turn up and get the RPMs I needed. It would also blow out badly. Tweaked the factory 3 blade by adding just a little more cup and it did great. 37 mph, no vibration, and did what I needed in the mud.