B31 prop size

[bmendenhall]

Good afternoon!

I have a B31 "Grand Slam" down in Venice, LA...Ive been away for a while but looking at getting back to regular fishing!! This B31 has 6bta 350's and prop pockets..It has a decent sized tower and it quite heavy when loaded down for an overnighter. I am looking to change the propellers. I'll try to send a picture of what is on her..but they are pretty small 3 blade props. Doesn't get out of the hole well and smokes. We've addressed the engines and feel most of the smoking is due to weight and props. I was on boat diesel and plugged in some specs and was recommended 4 blade props with some variablilty on size. I'd appreciate anyone's thoughts/experience on prop size, blade #, etc. Thank you. Brian Mendenhall

[TailhookTom]

Mr. Lico, paging Mr. Lico, Bob Lico, there is a Cummins propeller question!!!!

Tom

[IRGuy]

How is the condition of the bottom? More specifically, how clean are the props/shafts?

I have Cummins 6B 315HPs in my B33, and when the props get well covered with barnacles she won't get up to normal speed for the engine RPMs and she smokes a lot.. (Black smoke)

[Tony Meola]

The prop pockets change the dynamics.

How much clearance do you have in the pocket if you need to go larger? What size and pitch are you running now?

4 Blades will help a little, but if the pocket is limiting the flow of water to the prop then you have an issue.

[bmendenhall]

Thank you for the replies! I'm heading to Venice this week and am hauling it out so I'll have more info on the pocket size and prop size. As far as the bottom just had done last summer.. it is clean.

[bob lico]

the prop pockets on a 31 Bertram will direct aerated water to the prop nullifying any advantage of speed from less wet area.to take full advantage of prop pocket under the 31Bertram conditions as opposed to a catamaran whereby the water runs straight thru with props. on sponsons . you need 110 % 5 blade props.with full cup. these are quite expensive but OEM. on new boats with full length prop pockets . a four blade prop would be a step in the right direction from the current 3 blade.you need as much wheel as you can put in 21" diameter with 4 blade full cup you would be looking at a 22" pitch.

[bmendenhall]

That sounds like good advice! We will probably move more toward a four blade instead of 5 $$. With cold air and very little weight it ran great! No smoking and got up on the step immediately. But when loaded down for an overnighter and the air is hot totally different story. When I figure out how to add some pictures I will send them. Thank you!

[bmendenhall]

OK I give up. How do I post a picture from my phone?

[Navatech]

OK I give up. How do I post a picture from my phone?

You first have to upload the picture to some image hosting place like Photobucket...