viper prop

[max]

hi does anybody has expirience on viper props and e tecs.
175 hp. and 19 inch viper would be the set up.
or could i take an 21 inch.
the boat is total load around 1000 kg.

until now i had an rebel 19 inch and i think its not the fastest.

regards max.

[GordyP]

What revs are you getting with the Rebel at wide open throttle? I changed from Rebels to Vipers and they are very different props. To give you an idea i was running 19" Rebels and getting 5200 revs at wot, I then changed to 17" Vipers and got 6,200 revs at wot (too much), 19 " Vipers will give me 5,800 revs at wot.

Might be worth speaking to John Price at Quinquair Marine who is very knowledgeable on this. 01437 721911

[Chris]

A 19" Viper would be an ideal starting point for you. I have a 19" viper on a 6.5 meter and am getting 5,500 RPM at WOT trimmed out which is spot on.

Chris

[max]

Originally Posted by Chris

A 19" Viper would be an ideal starting point for you. I have a 19" viper on a 6.5 meter and am getting 5,500 RPM at WOT trimmed out which is spot on.

Chris

ok so 5500 rpm is the mark for the e tec or am i wrong. so ill i have to trie this first, with the rebel im around 5200 to 5400 rpms trimmed out.

[Chris]

Originally Posted by max

ok so 5500 rpm is the mark for the e tec or am i wrong. so ill i have to trie this first, with the rebel im around 5200 to 5400 rpms trimmed out.

5500 - 5600 is your ideal RPM at WOT.

[max]

Originally Posted by Chris

A 19" Viper would be an ideal starting point for you. I have a 19" viper on a 6.5 meter and am getting 5,500 RPM at WOT trimmed out which is spot on.

Chris

chris how many knots do you get at 5500 rpm with the viper prop

regards max

[Chris]

about 43knots with my current 150HP... however with a 175 on my boat I would expect to be able to run a 20 or 21" prop to get me up to about 47 knots. A lot will depend on your hull and how fast it is as you may be able to run a 20 or 21" unfortunately its a matter of testing the prop to see how you get on.

Do you have anyone you can borrow a 19" prop from to run some tests?

Chris

[Chris]

Originally Posted by max

ok so 5500 rpm is the mark for the e tec or am i wrong. so ill i have to trie this first, with the rebel im around 5200 to 5400 rpms trimmed out.

Sorry Max I have just noticed this post. It is a known fact that the Rebel will run at lower RPMs that the same pitch Viper so if you are going from a 19" Rebel to a Viper then you will find that you can run a higher pitch Viper. You are almost at the correct RPM with your Rebel so if I was going to switch to a Viper I would look at going to either 20 or 21. Unfortunately it is difficult to say which. I would be tempted to go for a 21".

You must also check to see that your engine is high enough on the transom as the E-tec engines like to run quite high up, as a rough guide the plate above your propeller (anti ventilvation plate) must be about 2" above the bottom of the transom when the engine is fully trimmed in against the transom. The ideal setting is so that you can see the top of this plate when the rib is planning See here ->> http://rib.net/forum/showthread.php?...ion#post311192

If you want really good advice on setting up an E-tec then go and have a look at this forum.

http://www.etecownersgroup.com

Chris

[max]

Originally Posted by Chris

Sorry Max I have just noticed this post. It is a known fact that the Rebel will run at lower RPMs that the same pitch Viper so if you are going from a 19" Rebel to a Viper then you will find that you can run a higher pitch Viper. You are almost at the correct RPM with your Rebel so if I was going to switch to a Viper I would look at going to either 20 or 21. Unfortunately it is difficult to say which. I would be tempted to go for a 21".

You must also check to see that your engine is high enough on the transom as the E-tec engines like to run quite high up, as a rough guide the plate above your propeller (anti ventilvation plate) must be about 2" above the bottom of the transom when the engine is fully trimmed in against the transom. The ideal setting is so that you can see the top of this plate when the rib is planning See here ->> http://rib.net/forum/showthread.php?...ion#post311192

If you want really good advice on setting up an E-tec then go and have a look at this forum.

http://www.etecownersgroup.com

Chris

chris now im getting 45 knots with the rebel 19" do you think i get more speed with the viper 19" or will i just have more grip?
thank you learnd alot

max

[Chris]

What Rib do you have Max?