The Viper Has to Go!

[Ian M]

I've been running a 19" Viper prop and have finally had enough! Poor hole shot and not such a good top end. The etec revs out to 5600 no probs, and gets there impressively quickly! So poor bite from the prop and I suspect that I am getting excessive slip. I've tried a 21" Rebel but it was too much and I only managed to get 5000 rpm. The local dealer is unwilling to get a prop in for me to try, despite recommending a 19" Rev4 4 blader. I have to buy without trying, which I am reluctant to do.
So, does anyone know of a dealer who might be willing to loan a 19" Rev4 for me to try? Obviously if it is OK, I'll buy it, likewise if a ding it
One of the factors that I want to try out is engine height, at the moment I am running one hole off of the bottom as the Viper is known to run higher than some props, hopefully dropping it one hole will be sufficient. I know it is a long shot, but has anyone any direct experience of a Rev4 on an etec on a 6.5 Vipermax?

[Pikey Dave]

Not quite, but I have rev4s on my twin 115s on a 6.4 ribcraft. Originally the engines came with 21"vipers, they were the equivalent of slicks on a car, no grip & continually blowing out in the rough or in turns. Mike Vincent at South Coast Marine suggested the Rev4s & I haven't looked back. He let me try 19 & 21" on a try before you buy, I went for the 19inchers. They are a bow lifting prop, in that they "dig in" & hook the stern down, consequently I don't need to trim up as much to get the nose up.
The only downside is that they aren't as fuel efficient as the vipers, with the vipers I was getting 0.78nm/litre, the rev4s get about 0.7nm/l. I was willing to make the sacrifice for the vast improvement to the boat, they really did make so much difference to the handling.
HTH

[martini]

Ian,
I've got a 19" rev4 you could borrow except for the fact I'm using them at the mo as one of my 17"s is sh***ed.

In fact re reading your post if the 19 viper gives correct rpm's then the 17" R4 is probably a closer match. It's my 17" LH R4 that's gone U/S so the RH is available for a short period while I save up for a new LH

[Pikey Dave]

Originally Posted by martini

Ian,
I've got a 19" rev4 you could borrow except for the fact I'm using them at the mo as one of my 17"s is sh***ed.

In fact re reading your post if the 19 viper gives correct rpm's then the 17" R4 is probably a closer match. It's my 17" LH R4 that's gone U/S so the RH is available for a short period while I save up for a new LH

How bad is the damage? Steel Developments have fixed price repairs regardless of the extent of the damage. IIRC they will rebuild a prop as long as there is at least 50% of the original remaining, worth a punt.

[martini]

Another one worth trying is a 19" Mirage plus. I've probably got one somewhere

Of course for either you'll need a flo-torq hub from Black Dog Marine

[martini]

Originally Posted by Pikey Dave

How bad is the damage? Steel Developments have fixed price repairs regardless of the extent of the damage. IIRC they will rebuild a prop as long as there is at least 50% of the original remaining, worth a punt.

There's a 1" crack at the base of every blade
Propellor Solutions (thought I'd give him a chance to redeem himself) were supposed to send me a special welding rod to have a bash with. It's hit & miss whether repairs like this work but I've given up waiting for the rod anyway, useless tw*t

[Pikey Dave]

Originally Posted by martini

There's a 1" crack at the base of every blade
Propellor Solutions (thought I'd give him a chance to redeem himself) were supposed to send me a special welding rod to have a bash with. It's hit & miss whether repairs like this work but I've given up waiting for the rod anyway, useless tw*t

I reckon Steel Developments would sort that for 89 quid

[Chris]

Ian,

I ran a 19" Viper on TimeBandit and it was perfect. Great hole shot and good top end.

How high is your ventilation plate above the bottom of the transom? What is your top end speed and RPM?

Does it sound like the prop is slipping when you drop the hammer ?

Chris

[Ian M]

Hi Chris,
Interesting! My experience is pretty much as PD's. Hole shot in particular is just terrible compared to many other RIBs that I have driven. With a 200 on the back of a 6.5 it should be much better than it currently is. Still I cannot shout too much until I have found a prop that performs better
Ian

[Chris]

Something to consider is that with the 200HP E-tec which is the same block as the 150 & 175 they remapped to get the additional top end power however in order to do so bottom end torque had to be sacrificed.

Could explain why the 150 had such good hole shot.