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so many newbie questions

B

bender

Member
I need help choosing a prop, the boats 15 feet and the engines a 406 chevy that makes most of its torque below 3000rpm`s (493 lb ft @ 2950rpm) , since I see blades don`t like being spun past 3000 rpm I figured i`d be good with a direct drive prop, any suggestions?


are the bottom of most hulls totally flat? and does anybody have any pictures of turnbuckles on an airboat?


thanks
 
Senchenich Q series is a good prop for DD and its adjustable pitch will let ya work with things on the engine and add HP as ya can.

Some boats are dead flat and some are slightly crowned in the middle of the bottom. Most Aluminum hulls are built flat. I put a slight crown in mine and others swear by dead flat. Both give gooid results from what I can see.

Never heard of a turnbuckle on an airboat. Whats the application?

You came to the right place for answers. Were all here to help eachother.
Glad ya found us and welcome to the forum.

Scotty
 
I have herd someone refer to jacks as turnbuckles before. That might be what bender means.
 
He is talking about a hull jack.

Think of a triangle that attaches to your outer ribs. Now the center of the triangle has a pipe through it. run a piece of all-thread through the pipe with a nut on each side. this all thread will push down on the middle rib. Make a saddle on the bottome of your all-thread so that it can slip off the rib. If you have more then 3 ribs in your boat you can weld several pipes to your triangle so that you can apply pressure to several ribs.
 
yeah i`m talking about a hull jack, I saw them referred to as turnbuckles in a few threads here so thats why I called em that, are these neccessary or just helpful for turning? I also catch alot of debate over trim tabs, some of my buddies say their a neccesity and others say you only need trim tabs if your hull isn`t built right.


i`ve never owned or operated an airboat so I wanted to start with something simple (sbc dd etc) once I get it finished I can pay one of ya for boating lessons :lol:

then maybe the old 540 from my malibu will find a new home in an airboat :twisted:
 
bender":2538gg7m said:
I also catch alot of debate over trim tabs, some of my buddies say their a neccesity and others say you only need trim tabs if your hull isn`t built right.
Click to expand...

Sometime's we can't believe everything our frineds tell us......

There is some truth to it though I guess...I like a little bitty bit of hop in my boat but if it was bucking me like Tuff Hedeman at the Rodeo than yeah something's not right with the boat. I still think it's better for hill running to run stern heavy (i.e. some bouncing) instead of bow heavy (plowing). I ain't no expert though.

Adam
 
Ok, hull jacks and trim tabe are as individual a thing as your underwear.

A correctly balanced hull doesnt need either to run flat and easily. If the boat won't run dry at all then the jacks will help but be sparing with them cause they have enough power to actually break the hull.

Trim tabs add upwards thrust to the back of the hull anytime the boat is moving. Most these days (but not all) prefer adjustable trim tabs so they can pull them up when they come out of the water onto dry land.

In general that upward thrust creates a vecdtor that works against the forward thrust of the engine. In plain talk that means it slows the boat down some in the water and a LOT on dry ground. Thats why we like to balance the boat with load and design first. Nobody wants a trim tab that doesn't have to have one. They do work and they work well.


I can think of no better a use for that Malibu's O-540 than to live its remaining days on the back of an airboat. I assume you aren't doing the progressive maintenance thing and are under commercial rules. Otherwise I suspect you would run it til it can't measure up. My friend has a O-470 in his Skylane with near 2900 hours on it and still good compressions and low oil consumption. He flies it very conservatively though at about 24/24, it pays on the other end to baby them.

Scotty
 
O- what now? I was talking about a big block chevy thats 540 inchs, I assume you thought I was talking about an AC engine?
 
Hahahahahah Yeh

Piper Aircraft has a Malibu model.

Duhh me

Scotty :lol: :lol: :lol: :lol: :lol: :lol:
 
bender":f57np6kw said:
yeah i`m talking about a hull jack, I saw them referred to as turnbuckles in a few threads here so thats why I called em that, are these neccessary or just helpful for turning? I also catch alot of debate over trim tabs, some of my buddies say their a neccesity and others say you only need trim tabs if your hull isn`t built right.


i`ve never owned or operated an airboat so I wanted to start with something simple (sbc dd etc) once I get it finished I can pay one of ya for boating lessons :lol:

then maybe the old 540 from my malibu will find a new home in an airboat :twisted:
Click to expand...

I run dual hydralic trim tabs and I love them. I like to set a boat up just a little heavy in the rear then I use the trim tabs to abjust the ride. I know this creates a little drag but it is worth it. The reason dual trim tabs are a dream is because you can balance your load without moving people or gear around. without trim tads if you are to heavy on one side the boat will pull left or right. I am a big duck hunter and I go out when the weather is real bad so I like trim the boat heavy in the rear when I have to run 3-5' swells this way I do not plow the waves and my passaners stay dry. Trim Tabs also allow you to plane out in deep water with ease.
 
i run a hydo trim tab and a jack in my 0-540 on a big O 12'6" fiberglass and i love them both, my fuse went out in my trim tab the other day and i had to straight wire it for the remainder of the trip but my boat will buck like Bodaceious without it...but my boat still runs the hill awesome and has top speed on water of like 48 or 49- thats good enough for me..... my buddies run those manual adjust trim tabs with a spring for they just push up when ur on dry and push down when ur in water, they seem pretty effective but i never ran one, so i think ill stick to mine for now, just an idea to think about- but i dont kno a lot about those spring trim tab deals- maybe u can ask around for more info... just something for ya to think about...
 
whatever gets me out there quicker is good enough for me, I just wanna get this boat together and learn how to operate it then start building something big for hunting and fishing, like a 20x8'6"

besides my neighbor wants to give me 3 times what i`ve got in it already, some of you airboat folk ain`t quite right :lol:
 
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