# Question on 2013 Etec 90hp



## lemaymiami (Feb 9, 2007)

Do what your dealer recommends (and ask them if they have a loaner you can try to get setup properly). I've run nothing but E-Tec 90's now since 2005 (my current one, number three is a year out of warranty, it's a 2012...). It has a 13 7/8 x 15 three blade Viper (for a starting point...). Nothing wrong with running a four blade - if it's not too much prop for your load. The one you have is obviously "too much prop" if you're only getting 4000 - it should turn all the way up to 6000....

Lots of talk about four blades for skiffs running shallow but also a drawback or two... A four blade will allow a stronger hole shot and a bit more "lift" but at the expense of top end and slight deficit in fuel economy as a result. That's why I run a three blade (I'm much more concerned about "legs" the range I can get with a given fuel load since I'm a commercial operator..).

Hope this helps.


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## efi2712micro (Sep 17, 2015)

It certainly does .... I will try the three blades to see. Out of curiosity, what sort of skiff do you have attached to these engines? Trying to compare payloads and hull profile. Thanks a lot


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## lemaymiami (Feb 9, 2007)

Mine is on a 28 year old Maverick skiff..... It's just under 17' long and weighs in at 735, bare hull. A 90 is a bit under powered for this skiff - I used to run 115's on it...


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## Vertigo (Jun 3, 2012)

I run a 90 hp Etec with a Powertech 15 pitch 4-blade on an 1872MVT Seaark, which is not the most efficient of hulls. My WOT rpm is between 5400 and 5500 depending on load and conditions. Something is seriously wrong is you're only seeing 4000 rpm. Have you considered that the tachometer might be wrong? What speeds and prop slip are you seeing?


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## efi2712micro (Sep 17, 2015)

Hi Vertigo ... my tach is an icommand gauge. I only get 28 mph on the HDS 7 @ 4000 rpm. I do believe the rpm is consistent with the speed for that boat. I am not sure how you measure prop slip as I am still learning all of this. Cheers


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## jmrodandgun (Sep 20, 2013)

What is the diameter of the prop?


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## efi2712micro (Sep 17, 2015)

Hi JM

Asked someone to measure it for me and they got 14".

View attachment 2638


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## lemaymiami (Feb 9, 2007)

If it's a BRP prop you'll find the dimensions info stamped into the rear face of the hub (right where the prop nut is....). If no info there, whose prop is it?

Pretty tough to work up a prop for a motor if you're using a used (maybe modified more than a little by the last owner) prop to start with....

I might be wrong but I'd sure bet your BT, being a lot lighter and certainly more modern than my 28 year old Maverick, ought to fly once you have the right prop (and it should do a lot better than the five miles per gallon that mine provides...).


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## jmrodandgun (Sep 20, 2013)

That is bizarre. It should be turning faster with that prop. I don't know man, I'm stumped. 

4 blade props generate a lot of lift. You very well may be lifting the stern of the boat and burying to bow. Could the motor be in the wrong spot? Too low on the transom? Trimmed in too far? Too much tab? The are complete blind guesses.


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## tjtfishon (Feb 9, 2016)

efi2712micro said:


> Hi Vertigo ... my tach is an icommand gauge. I only get 28 mph on the HDS 7 @ 4000 rpm. I do believe the rpm is consistent with the speed for that boat. I am not sure how you measure prop slip as I am still learning all of this. Cheers


http://www.csgnetwork.com/marinepropcalc.html

I'm no expert, but 10-15% slip is probably reasonable. Under 10% is exceptional


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## Vertigo (Jun 3, 2012)

At 4000 rpm, 28 mph, with a 15 pitch prop, slip calculates out to 1% which is almost impossible. It could be that your prop is not 15 pitch. It the prop were 17 pitch the numbers would make more sense. If you can't determine the pitch of the prop by numbers stamped on it, take it to a prop shop and have someone measure it...or just buy a cheap aluminum 15 pitch and test it out to see how the boat runs.


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## efi2712micro (Sep 17, 2015)

So finally called Will at Beavertail and he told me to replace the powertech CCF4 prop (14", 14 pitch and some serious cupping) with a brp rogue 13.25 x 15. Got 5300 rpm WOT and 38 mph. More like it .... thanks ya'll for your help and insights. Didn't realize a prop could make such a difference!


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