Motor vs. draft

fredindeed

Recruit
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Feb 4, 2022
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2
I’m curious as to how low a 17 xpress crappie will sit in the water with a 90hp Yamaha 4stroke? The river is pretty shallow. Thx!
 

Bob Sander

Petty Officer 2nd Class
Joined
Nov 29, 2021
Messages
120
That motor weighs about the same as 2 medium-sized guys. Have them stand in the back of the boat close to the centre transom area and you will have your answer.
 

fredindeed

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Feb 4, 2022
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Im looking to buy and its on a trailer. I know it weighs 375 or so. I dont want to have to have pods
 

robert graham

Admiral
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Apr 16, 2009
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6,908
My boat is a 1870 Express with a 268 lb. Yamaha 2 stroke on transom…it sits 5 inches in the water at the transom. The width of your boat is a big factor…The weight of the motor( in your case about 100 lbs. more than mine) is another factor…What is your boat width at the transom?
 

racerone

Supreme Mariner
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Dec 28, 2013
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37,816
Google-----Find the express website.----The phone # ( 501 area code ) and E-mail for them is all there.----They will know !!
 

Texasmark

Supreme Mariner
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Dec 20, 2005
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14,665
Weigh the contents and the boat. Calculate the area of the boat to be in the water. Take a cubic foot of water at 7.5 gallons of water at 8.3 pounds per gallon and .

The boat will displace the amount of water equal to its weight. Since the hull isn't perfectly rectangular and the answer would be for the load being equally distributed....like to offset the weight of your engine, move folks and gear forward, you ought to be able to get some idea as to its draft.

Tiller vs remote steering certainly plays into this calculation and makes a whopping big difference in how low the transom sits.....moving the fuel tank from behind the last seat up forward the length of the fuel line helps too.

Crappie boats are usually long and narrow. That works against you. Wide transoms help a lot in shallow draft floating.

If you are snow bound, it might give you something to do to pass the time. So lets kill some time. Referincing: https://xpressboats.com/crappie/ H17C with the 90 Yammie:
Boat 1165#, 10 gallons of fuel, engine 375, 2 avg. guys 350, tackle 150, livewell empty, beer....TBD = 2115#

Taking the hull assembled into a rectangular cube I estimate the average transom width (93-67)/2 +67 to equal 80" wide.
Taking the way the hull is shaped I am going to take 14' for the length. So looking at the area 1' deep for a cubic type measurement I come up with displacing 255 gallons which is only 34 cu. ft.
That quick estimate says that the water line will be 1/3 of a foot above the bottom or 4" draft. With 22" sides and what folks normally do, with the helm mid-ship which really helps,I would anticipate an 8" draft overall while fishing and folks moving about and all.

Underway, you will be deeper than that due to the transom sinking till up on plane....expect maybe as much as 12" plus engine. If you mainly idle along with the the engine tilted up that's one thing. If you want to hammer down on the throttle and get on plane where your skeg clearance might be 13" for the prop plus 4" draft, you are looking at minimum 2' depth for my best guess.

In coastal areas they use tunnel hulls for shallow water fishing where you can run on plane and get there in just a few inches of water. This is just a WAG but it is a set of numbers and something for you to think about.
 

southkogs

Moderator
Staff member
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Jul 7, 2010
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14,919
Xpress didn't put the draft of the boat on the website (that I could find). If you don't already own it, I would call / email the dealer or manufacturer and see what they say draft is. - Then you can start adding in crew, rigging and "load."
 

Bob Sander

Petty Officer 2nd Class
Joined
Nov 29, 2021
Messages
120
Im looking to buy and its on a trailer. I know it weighs 375 or so. I dont want to have to have pods
I would suggest that the difference in draft with a smaller motor (say 40hp) and a 90 will be MAYBE a couple of inches on the average boat.

Either way though, if a couple of inches is seriously going to be the difference between 'make' or 'break' then maybe a row boat or a canoe would be the safer bet, because you are too close with BOTH the 40 and the 90.
 

KJM

Lieutenant
Joined
Jul 31, 2016
Messages
1,265
How deep is the water anyway? I agree with Bob, if you got to worry about inches then I wouldn't chance damaging an expensive motor in that area anyway. A good wake wave from a passing boat could do a job on you!
 

ahicks

Captain
Joined
Sep 16, 2013
Messages
3,957
I’m curious as to how low a 17 xpress crappie will sit in the water with a 90hp Yamaha 4stroke? The river is pretty shallow. Thx!
I'm wondering "as compared to what" would be key to gaining any practical info? Another boat with that same 90, or that same boat with different power?

Would an inch of draft (one way or another) matter?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
37,816
Perhaps a jet lower unit model will help.-------Or ask the dealer if a " shortshaft " motor will do the trick.
 
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