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Old 02-11-2008, 07:04 AM
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kevcros
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Default Boat Draft ?

I am comparing various outboard rigs with straight inboard rigs in the 30-35' category-- I have shallow water to deal with and want to compare hull drafts-- Many of the inboard rigs are HULL drafts of 36" or more-- How much more is needed for the prop (i assume another 24"-- 36" minimum)--

So the difference between outboard and inboard is probably 36" of overall draft---



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Old 02-11-2008, 07:07 AM
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Default Re: Boat Draft ?

An inboards draft should include your running gear. In the 30 to 35' range you should be not much more than 36" unless your are looking at displacement hulls.
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Old 02-11-2008, 07:07 AM
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Default Re: Boat Draft ?

Most props don't extend below the hulls deepest draft.
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Old 02-11-2008, 10:34 AM
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Default Re: Boat Draft ?

i agree with both of the above.

depending what type of boat you are looking for you can find some inboards built into prop pockets or like the dorado 40 that is a tunnel drive boat and only drafts like 24" or so
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Old 02-11-2008, 11:06 AM
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Default Re: Boat Draft ?

Agreed, I have a 38' and Draw 40" with a semi-displacement. That is to the base of the running gear rudder being the lowest point
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Old 02-11-2008, 11:57 AM
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Default Re: Boat Draft ?

Do you mean, how much water you need under the prop to use the boat? The draft figures the mfg gives are to the lowest part of the boat, whther it is the props, or on some deep-vee's, the forefoot. You will need 12" at idle speed for prop clearance and 24-30" at cruising speed. Witha 35' boat, you will need 5-1/2' to6' of total water depth to operate it.
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Old 02-11-2008, 12:21 PM
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Default Re: Boat Draft ?

LI32-- Thanks-- I also assume that you need at least 5' to comfortably run a 35 straight inboard with a 38" draft (obviously hurts alot more when/ if you hit bottom)--
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Old 02-11-2008, 01:36 PM
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Default Re: Boat Draft ?

If you want to operate in shallow water, look at commercial boats that have to run in shallow water. Foot for foot there are big differences.

Compare a Chesapeake deadrise workboat hull to a similar length downeast hull. The Downeast hull will draw about a foot more. My deadrise has a draft of a tad over 3'. The Albin sig boat needs about 3'9". Each has it's own good & not so good characteristics. At the moment I own a 32' example of each. For operating in tight spots I'll take the workboat anyday. For straight tracking the longer keeled downeast style hull wins.
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Old 02-11-2008, 01:55 PM
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Default Re: Boat Draft ?

The situation is a s follows-- I have a shallow dock situation that is tidal (1' at low tide and 8' at high tide)-- I am comparing inboards and outboard boats and am now leaning towards outboards to maximize my dock usage-- I would be fairly comfortable running my OB at 3' but i know that my inboard comfort factor is probably 6'--

What would you choose ?
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Old 02-11-2008, 02:35 PM
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Default Re: Boat Draft ?

Quote:
kevcros - 2/11/2008 4:55 PM

The situation is a s follows-- I have a shallow dock situation that is tidal (1' at low tide and 8' at high tide)-- I am comparing inboards and outboard boats and am now leaning towards outboards to maximize my dock usage-- I would be fairly comfortable running my OB at 3' but i know that my inboard comfort factor is probably 6'--

What would you choose ?
Once this global warming thing gets up to speed you'll have a lot more water at low tide.

I'd say it's a no brainer - outboards. You can tilt the motors out of the water when docked and let the hull rest on the bottom. I wouldn't want my prop and rudder resting on the bottom.
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Old 02-11-2008, 09:28 PM
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Default Re: Boat Draft ?

In my opinion outboards and you would better worry about low tide and deadrise. You may need to add "legs" to keep the boat vertical. Unless it can badly lean one side or another, and let water enter by some drains.
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Old 02-12-2008, 04:21 AM
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Default Re: Boat Draft ?

If you only have 1' of water at low tide, a 30-35' inboard boat is going to be sitting on the hard and 1-1/2' to 2' out of the water - you can't let an inboard sit on its running gear. Frankly, I would be concerned having any boat sit on the ground every tide cycle - there may be rooks or other debris that will damage the hull, not to mention uneven loading on the grounded sections, both of which will be exacerbated by wind or waves. I know up in Maine and Nova Scotia some guys let their boats sit on the hard on low tide, but those are either flat bottomed outboards or boats with keels that they have a block setup on the hard that keeps the boat upright when the water is gone. Since you can only use the boat when the tide allows, outboards and a poling stick seems like a better choice.
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Old 02-12-2008, 06:45 AM
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Default Re: Boat Draft ?

I'm thinking a lift is in order here. I would still go with outboards just to make it easier and safer to get in and out.
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