Tri-hull shallow water question

[jarrpal001]

was wondering whats the shallowest a trihull boat can be in? i have a 72 thunderbird shawnee.

 

[a1akeywest]

Re: Tri-hull shallow water question

i guess that would depend on the design of your specific hull and how far down your prop runs...

 

[DaNinja]

Re: Tri-hull shallow water question

Just guessing that our tri-hull needs a little more water than the T-bird.

 

[royal0014]

Re: Tri-hull shallow water question

Depends on a couple of factors. Best to load up the boat like normal, find some skinny water, and break out the paddle. Just use some common sense. Like a good woman, skinnier isn't always better


<<)))(((>>

 

[tboltmike]

Re: Tri-hull shallow water question

Depends if static or on plane. Tilt angle is a factor too.

Once, I had my tri on a good plane and things started feeling funny, not haha. Looked back to see a dirty wake. Couldn't trim and turn quick enough to get back to deep water. Everyone got out, including ice chests. Took 30 minutes of pushing, shoveing, rocking and twisting to 20 yds to deeper water.

 

[shrew]

Re: Tri-hull shallow water question

Draft is unique to each boat. There is no single value for draft based on the hull type. Displacement, LOA, Beam, overall weight, running gear, and weight of occupants and gear will all affect draft.

My personal rule of thumb is, "If I can stand in it, I don't really need a boat anymore".

 

[Home Cookin']

Re: Tri-hull shallow water question

another question like "should I walk to work today?"
You don't say enough--like do you mean "shallowest to be in" to run on a plane? Idle? float? Moor?

for skinny water boaters, running aground, stirring bottom, etc. is common experience and nothing to worry about if you know what you are doing.

Talking boats <20':

Deep V's tend to require more water at low speeds; on a plane they are about all the same. the motor depth is way more the factor than hull design, although a broad flat bottom will obviously float higher than a narrow or keeled bottom.

What is advisable is largely driven by the bottom--soft mud, hard sand, rocks/stumps. We run over soft mud all the time because of low risk of damage, and are careful over hard sand (low risk of damage at low speed). Couldn't operate that way over rocks. Also mistakes can be fixed, or worsened, by tide.

You just have to learn your boat and waters by experience.

 

[Bondo]

Re: Tri-hull shallow water question

was wondering whats the shallowest a trihull boat can be in? i have a 72 thunderbird shawnee.

Ayuh,... With the boat sitting, at rest, in the water,...
Put a pencil mark At the waterline, at the transom....

Put the boat back on the trailer, 'n lower the motor All the way...
Then Measure from your mark, to the bottom of the skeg....

That's how much water you need at displacement speeds...
It'll be a couple inches less at Plane...

 

[jarrpal001]

Re: Tri-hull shallow water question

thanks guys especially master shipwright for your info. thats what i needed

 

[64osby]

Re: Tri-hull shallow water question

I agree w/ Bond-o

Ayuh,... With the boat sitting, at rest, in the water,...
Put a pencil mark At the waterline, at the transom....

But also make sure you add weight of gear and people when marking water line, 2 people could add up to 500 / 600 lbs depending on their size and gear.

Or you could load up and go looking for sand bars, when you get stuck measure the depth and add to that.

 

[smallboatlover]

Re: Tri-hull shallow water question

I know from experience that my 14' tri hull with a 50hp motor and 400lbs of extra weigh including me. it will float with the motor up in about 5" of water. I have to paddle out of my local boat ramp at low tide. i broke the prop the first time out because of how low it was, but you can probally get to about 4". That with my trihull i don't know about yours, if its heaver or lighter.

 

[5150abf]

Re: Tri-hull shallow water question

You want to be really careful in skinny water, you may get away with the first couple prop strikes then your lower will explode and I have 2 lower cases in the garage attic to prove this point.

If you can boat anywhere else do it, skinny water is best run in a flat bottom jet boat, anyhting else is asking for trouble, as to how shallow you can run in it depends on a lot of different thisgs and you will probably have to find out o your own, just be carfull.

 

[mrdancer]

Re: Tri-hull shallow water question

A true shallow-running boat will truly run shallow. I've seen smaller, 15-foot aluminum boats with pocket tunnels run in three inches of water, and float in six. I've seen bigger boats run in less than six inches and float in less than ten, all while swinging a 14-inch prop. But, you have to know what you are doing and you have to have the proper equipment. Your standard boat operator will say it is impossible because it is out of their box of thinking, but it happens all of the time. Check out the TX flats boats.

Back on topic - if your boat has been in the water much, there is generally a waterline stained into the hull of where it typically floats - this will give you the pencil mark that Bond-O is talking about. If it were a flat-bottom, you could calculate how much the boat would draft by some quick math (length at water line X width at water line) and knowing the weight of the boat, and knowing that you have 63lbs (saltwater) floatation for each cubic foot of displacement. For a non-flat-bottom, you will have to guesstimate where the bottom would be if it were a flat bottom, if that makes any sense.