What shaft length is this engine..??

[RichBKK]

I recently rebuilt a 1980 MirroCraft "Deep Fisherman".. The boat had a 15" transom with a "Mini Jacker" plate attached to raise the 2010 30hp ETEC to 20".. Anyway, I yanked the "Mini Jacker" plate and ripped out the 15" transom and built the transom to be 20 1/2".. I mounted the Evinrude and the cavitation plate is 2" below the keel.. I called a buddy who had owned a marina for 13 years and he measured from the engine mount (that sits on the top of transom) to the cavitation plate.. It comes out to be 22 1/2" in length.. He's said he's never seen anything like it.. Do I just have a one of a kind freak or are we possibly measuring wrong..?? We can't be measuring my transom wrong, it's exactly 20 1/2 inches..

Thanks for any and all help..

 

[boobie]

Re: What shaft length is this engine..??

What's the model # of the mtr ??

 

[JB]

Re: What shaft length is this engine..??

Is your transom 20.5" vertical or on the surface. If it is not vertical you need to measure the vertical distance from the top of the transom.

I suspect that your transom has an angle.

 

[RichBKK]

Re: What shaft length is this engine..??

Thanks for everyone's input.. Model #: E30DRLIIG.. 4/2010.. Serial #: 05295857..

Yes, the transom is "angled" and I used a yardstick, held flat against it, to measure it, top to bottom..

But, I've never seen a transom on any aluminum boat that was "built" above the gunwales and back of the boat.. The transom's are all "level" (straight across) from stern portside to stern starboardside..

Thanks for any help you can provide..

Richard..

 

[nwcove]

Re: What shaft length is this engine..??

Is your transom 20.5" vertical or on the surface. If it is not vertical you need to measure the vertical distance from the top of the transom.

I suspect that your transom has an angle.

just to elaborate on JB's point. "A" squared ( A=effective shaft length 20.5") + "B" squared ( B = distance of cav plate from transom..lets say 8") = C squared ( C = length needed for angled transom )

(A)20.5 squared+(B)8 squared=(C) squared 484.25.
square root of "C"=22".

Just by that example your transom would need to be 22" to get the cav plate 2" above the keel.

or 23.9" to get it even with the keel.

 

[boobie]

Re: What shaft length is this engine..??

Read JB'S reply again on how to measure a transom. The key word is "vertical" from the top of the transom to the bottom of the boat.

 

[steelespike]

Re: What shaft length is this engine..??

I can't speak for the etec but older OMC motors I have measured the 15" motor was actually 17"
Is there no vertical adjust on the Etec 30?
Further research it appears you may be able to raise the motor 3" or so.
Going by the height of the top mount hole. It would be closer to the edge but you could add a piece of flat stock or angle iron.

 

[boobie]

Re: What shaft length is this engine..??

According to the model # the mtr has a 20 " shaft length.

 

[Chinewalker]

Re: What shaft length is this engine..??

They all do that. What they mean is that it is for a 20" transom boat (or 15" for short shaft), with some wiggle room built in for differences in hull design, transom angle, keel depth, etc. Different manufacturers of both boats and motors treat it slightly differently, depending on what works... Highly doubtful that you'll find any outboard that is exactly 15 or 20 inches or any boat that is exactly 15 or 20 inches...

 

[RichBKK]

Re: What shaft length is this engine..??

My extreme apologies everyone, for the extremely late reply..

Here goes:

So I take my boat to a welding shop and we fabricate a "bar and plate" to fit on top of the "end cap" and transom, meausing 2 1/2 inches high, sitting / bolted on top of my transom and end cap..( I'd made / fabricated my transom, measured top to bottom, to be 20 1/2 inches high.. )

Test drive her and at the slightest "yank" on the tiller, she'd cavitate.. But, flat out wide open throttle, straight ahead-----she was a "Wild Mustang running the great plains of Kansas"..!! FAST..!! I mean----FAST..!! (but, she cavitated when "yanked")..

Anyway, dropped her an inch, (exactly 1/2 inch below the keel of the boat) and she doesn't cavitate a bit, but nowhere near as fast at wide open throttle.. Oh well.. I can live with it.. She seems to be getting better "mileage" than she was before when she was 2 1'2 inches "too deep" and has better responce and performance..

But, those 15 minutes when she was set "too high" and running in a straight line-----that's what dreams are made of..!!

Richard

 

[steelespike]

Re: What shaft length is this engine..??

Your experiencing "ventilation" Used to be called "cavitation" even in manuals of the day.
A prop from Turning Point may help your ventilation problem So you can go back to the better height.
May also add a little speed.

 

[RichBKK]

Re: What shaft length is this engine..??

I should "fill in a few blanks" here about the boat.. As mentioned before, she's a 1980 MirroCraft, semi-v hull.. Her "from the factory" weight was 196 lbs.. She had been "modified" by a mullet fisherman when I bought her.. The middle seat was pulled out and an aluminum frame had been made to enclose a large igloo cooler.. A casting / fishing deck had been made and installed that covered the bow and front seat.. It weighed a ton but helped to keep the bow down..

Anyway, I yanked the cooler and removed the casting / fishing deck and built an 8 foot long, 3/4" deck.. Much, much better, both from a fishing and performance standpoint.. Including the rebuilt transom, 3/4" decking, 1/8th" aluminum angle iron and stainless steele hardware, I probably added (guessing) close to 200 lbs.. An additional 6 gallon tank and 12' gas hose and bulb has been added to accompany my 3 gallon tank and hose.. That alone really extends my travel capabilities but, does add an additional 42 lbs or so..The weight does help lower the center of gravity and helps to keep her from pounding when headed into a chop..

I "up'ed" the stock prop also, going from a chewed up 10.3x12 to a Solas 10x14.. Doesn't have the snappy holeshot now but I'm not into a fast takeoff.. I want a long "engine life" and maximum miles per gallon.. And a wide open throttle maximum speed when needed to get back inshore safely as I do venture quite far offshore (8 to 10 miles chasing diving birds and baitpods)..

In hindsight, I should have gone with a "Turning Point" prop as everyone here in the forum seems to rave about them.. And, will probably go with a 10x13 next time..

 

[RichBKK]

Re: What shaft length is this engine..??

Oh, I might want to add that when she was on the 2 1/2" "bar and plate" fabricated transom (and her WOT was incredible), I was worried about her overheating, burning up the impeller and water pump because of the "cavitation / ventalation".. She was still peeing but----..