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doughickey

ACTUAL Draft measurement

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doughickey

A while back, there was a fairly lengthy debate (with pictures) about the actual draft of an RLX. many of us had our boats laid up in storage.... so lots of talk and speculation.... but no proof.

My RLX brochure from 1998 (and for years following) quoted the draft at 16". I always thought this was rubish. Apparently, Malibu just updated (finally) the brochures to read around 22". THAT"s when the debate started.

Regardless, it becomes important if we're planning to navigate shallow water, or planning to build a marine railway or boat lift etc etc etc.

On the past weekend, I did the measuring that say my RLX with 1/2 tank of gas requires 22 1/2 " of water to float. (This does NOT add anything for wave action, people, etc.)

Here's how it breaks down.

Distance from the very tip of the lowest blade of the prop (13" X 11.5" OJ 3 blade) was 14.5" to the bottom of the boat. (Hanges down LOWER than the rudder.)

Distance from the bottom of the hull to the exhaust port is 1".

Diameter of the exhaust (OD) is 5 1/2" (see picture)

Distance from the top of the exhaust to the water level is 1.5".

Total = 22 1/2". Absolutely NOT the 16" in the brochures!

(I wish Tom was still around for that wager....)

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Rod S

16 inches is underway at 34 mph.

Biggrin.gif

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NorCaliBu

ROFL.gif No one here to argue with you Doug. Tom was the only one sticking with numbers closer to Malibu's original claims. I think that everyone else here knew you were right on that one. Send TR a PM or an e-mail with a little... Tongue.gif

:)

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doughickey

I wouldn't dare consider a pm or email to Tom. Think I'll just let things stay the way they are... Interesting idea though Michael.

I guess Malibu finally figured out they should quote "draft" like the rest of the marine industry.... the water depth required at rest.... not while on a plane... at 34 or 28 or 36 or any other speed while underway. Who knows, maybe they had some lawsuits from underwater collisions that caused them to requote the actual draft numbers. (Damaged wedges comes to mind....)

Rod, if it is draft at 34 mph (logical answer by the way), have you seen Malibu post that anywhere... or (seriously) is that some other kind of "standard" that is used somewhere?

Thanks.

Edited by doughickey

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mlange

So, I guess this means if you see the depth guage start to drop you should hit the throttle to get up to speed? :)

Kinda like speeding up when the light goes from green to yellow.

Edited by mlange

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M3Fan

I'd imagine the tracking skegs are lower drafting than the prop. It surely is on my SN.

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Rod S

Doug, it was just an educated guess. Years ago when I first got my Response I measured for draft as I have a very shallow slip. At the time I figured that 16" was the bare minimum IF you were on plane not while sitting still.

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SmoothWaterMan

Nope, prop is the lowest on a Malibu.

FYI - 2005 Sunscape 23 LSV draws 26.5" at rest.

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doughickey
Doug,  it was just an educated guess.  Years ago when I first got my Response I measured for draft as I have a very shallow slip.  At the time I figured that 16" was the bare minimum IF you were on plane not while sitting still.

I think your 16" @ 34 mph guess is probably bang on!

Yes, when you see rocks up ahead, just hammer the throttle to reduce the chance of destroying your prop!!! Cry.gif

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Boomer

Maybe I missed it, but why the big obsession with draft numbers, and how accurate they are?

Who freaking cares? lol

Any inboard is in the same league as far as draft goes. It's not like one is 24 inches, and another is 3. Different inboards might vary a few inches, but are all in the same area.

I can't see this number meaning much to a person in the market for an inboard, unless you have a way to determine your water depth to the nearest inch, and your lake has a table-flat bottom who's depth never changes.

What's the big deal?

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doughickey
Maybe I missed it, but why the big obsession with draft numbers, and how accurate they are?

Who freaking cares? lol

Any inboard is in the same league as far as draft goes. It's not like one is 24 inches, and another is 3. Different inboards might vary a few inches, but are all in the same area.

I can't see this number meaning much to a person in the market for an inboard, unless you have a way to determine your water depth to the nearest inch, and your lake has a table-flat bottom who's depth never changes.

What's the big deal?

In my case, 2 reasons:

1/ My lake is split in 2. Narrow twisty river that goes under a bridge. Water depth is supposedly kept at 24"..... but water fluctuates 4" up/down through the season. The difference between 16" and 22" is VERY critical to me. It cuts my "boating pleasure" in half. It's why I use my Minn Kota trolling motor to idle (at 1 mph) through this dinky channel vs using the main motor (idle speed 5.1 mph).

2/ At my dock. I have a sloped sandy bottom. Again, water level fluctuates 4" +-. I also have to consider waves. When I bought my dock, it was important for me to know draft. Had the draft REALLY been 16", I could have got by with a shorter dock..... since I would have had more water to float the boat in closer to shore. I assumed 22".... so bought a longer dock section... and glad I did.

Likewise, anybody planning on building/buying a marine railway and/or lift needs to know how much draft... in order to know where to locate their lift etc.

To most, the difference between 16" and 22" would be irrelevant. However to others, very critical.

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VinRLX
Maybe I missed it, but why the big obsession with draft numbers, and how accurate they are? . . . What's the big deal?

Accuracy of information. Malibu was either publishing incorrect numbers knowingly or measuring from the bottom, which is NOT the way draft is measured. Not a relavent analogy, but how would you like to buy a boat with a 400 hp engine only to find out later that it's really 375? Maybe more to the point would be LOA. Some lakes are restricted to boats 20' or less.

Then there are people trying to set up lifts (or railways) for the first time. This is how I first realized the previous draft measurements were incorrect. The bunks on my lift (and likely most others) are high enough to clear the fins, but not the prop. Gotta know where to stop when you park it unless you like pretzels with a tear in your beer.

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VinRLX

Oh, and BTW, why do you figure they bothered to change the numbers after all these years?

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doughickey
Oh, and BTW, why do you figure they bothered to change the numbers after all these years?

My guess... "lawsuits or potential lawsuits" from unhappy owners after underwater collisions. Angry boaters trying to blame someone else, and quoting the brochure that says 16".... when it's really 6" deeper.

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88Skier

I always thought the 16" must not have included the running gear, which made about as much sense as if they gave the weight without the engine.

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VinRLX
which made about as much sense as if they gave the weight without the engine.

How do we know they don't? Anyone weigh in at a public scale?

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VinRLX
Oh, and BTW, why do you figure they bothered to change the numbers after all these years?

My guess... "lawsuits or potential lawsuits" from unhappy owners after underwater collisions. Angry boaters trying to blame someone else, and quoting the brochure that says 16".... when it's really 6" deeper.

Yup. I posted that exact possibility two years ago.

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