New guy 2 props

Airboat propeller discussion.
Post Reply
Ar Farmer
Southern Airboat Member
Posts: 1
Joined: Wed Mar 28, 2018 8:20 pm

New guy 2 props

Post by Ar Farmer »

I'm sure this is the first of many questions I will have even though I have had many answered by reading thru many pages of past subjects. I have inherited a 13'Cottonmouth with a supposedly 500 Caddy DD, not confirmed that it's not a 472 yet. It's been sitting several years so we have been going thru it from poly to air cleaner and everything in between. The man who owned it has passed away so he can't answer my questions so I found this site. It has a 78x30 wood prop that has some deteriation, soft wood so I am afraid to spin it. He had a new Sensenich 74x44 that I got with it. Here's my question, how different will these props act ? Can I pull this new one ? The boat is set up for 2 people but I remember we used to run with 3 sometimes. I assume the motor is stock . Thanks

User avatar
Site Supporter - V
Site Supporter - V
Posts: 4596
Joined: Thu Jan 06, 2005 11:16 am
Location: Inverness, FL

Re: New guy 2 props

Post by Deano »

I would not spin a 78" wood prop that has any deterioration or soft wood. That sounds like a clock to me.
If it were in great shape and you could use it, it would be slow(er) to plane and would be louder than need be.

The 74x44 is much closer, but will most likely be to much prop for anything less than a strong 500.
If you have a 500 and it is a regular stick prop (ie. not a paddle prop) that should work fine if your engine is healthy.

Measuring the stroke through a plug hole is easily done with a straw, pencil or something similar.
A 472 will measure a skinny 4 1/8", whereas a 500 will measure a fat 4 1/4".

On a different note, the first, best thing you should do is replace the timing chain with a Cloyes timing set. If you've researched Caddy threads here, you've already seen and heard about that logic. No need to repeat all that here again, other than to point out you DO NOT want to overlook this as a necessity. I believe the Cloyes # is 91-139, although that is here elsewhere as well.

Good Luck with your build, you came to the right place.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan

User avatar
Site Supporter - II
Site Supporter - II
Posts: 8569
Joined: Wed Aug 22, 2007 10:31 pm
Location: cocoa

Re: New guy 2 props

Post by JAMES »

78/30 vs 74/44 big difference are they both stick props or is one a paddle or both paddles ? When i ran mine i was using a 76/32 stick it did well but the 72/44 paddle was the ticket lot better push wood is ok but if their shot upgrade get a carbon safe and updated !! Wp383 268 rotator 3 bld WT/EX 14.4 perdator

Post Reply

Return to “Prop Talk”