Osprey Vipermax 7.00 issues

[Mollers]

Originally Posted by Cookee

I would go and check your information on the above - not sure where you got all of that from but as far as I know it's all a bit different to that.

WTF do you know about it?

[gotchiguy]

Ok, I hope Jean-Charles doesn't mind, but I have uploaded a couple of pics of the boat as it is. I don't know what position
the lift was in but in the second it would appear he was accelerating so I doubt that it would be at his highest point.
In my opinion the the engine needs to be lowered. I have included a quick picture of ours just to act as a guide at the bottom.
I have already told him how much I admire the black tubes with black engine. Top job

[gotchiguy]

Originally Posted by Mollers

WTF do you know about it?

Well it's come from listening and reading on here and on the etec Owners group forum. If you think it's different then I really would like to know how, many people have different views on the HOs and XSs but AFAIK they are all regarded as having around 15-20% more than rated. Same with Yam Vmax.

[Vipermax]

Originally Posted by gotchiguy

Ok, I hope Jean-Charles doesn't mind, but I have uploaded a couple of pics of the boat as it is. I don't know what position
the lift was in but in the second it would appear he was accelerating so I doubt that it would be at his highest point.
In my opinion the the engine needs to be lowered. I have included a quick picture of ours just to act as a guide at the bottom.
I have already told him how much I admire the black tubes with black engine. Top job

Hi Oliver,

No pb about the pic. But I think they are very representative. Indeed the man at the wheel is not me but one my friend and he was trying somethin with the lift.

But anymay you may right I will lower the engine as soon as possible.

Other thing I forgot to say is that the top speed is reached with the lift between 2cm 2,5cm if its clearance. Which makes the total height of the anticavitation plate between 10cm and 10,5cm above the hull at WOT.

Hope it will help.

Jc.

[gotchiguy]

Originally Posted by Vipermax

Hi Oliver,

No pb about the pic. But I think they are very representative. Indeed the man at the wheel is not me but one my friend and he was trying somethin with the lift.

But anymay you may right I will lower the engine as soon as possible.

Other thing I forgot to say is that the top speed is reached with the lift between 2cm 2,5cm if its clearance. Which makes the total height of the anticavitation plate between 10cm and 10,5cm above the hull at WOT.

Hope it will help.

Jc.

You might like to remove the [img] things from your post, it clutters up the thread me putting big ones in the first place, but having them a second time makes it a little hard to navigate. Just click "edit" in the bottom right corner then delete the lines of text which are [IMG] there should be three.

[Cookee]

Originally Posted by Mollers

WTF do you know about it?

I raced against a 200HO with an XR2 (barely 195hp) so I did my homework and I also raced XS's

Evinrude have never published any performance figures for their HO range, they were a cheat for the Bass fishing boys who were limited by horsepower and were only 10% over not 20%. Only the latest XS is overpowered, every XS before 2010 was what it said on the label. Bass boats use Sportmaster gearcases and the Evinrude box is the same for offshore and in Offshore racing it's the saddle that breaks - I've seen it. Generally a Mercury saddle and gearcase with a low water pickup has been hard to match for many years, especially the 15" Offshore leg which is why they have been so popular, it's a shame that the other manufacturers have never tried to match them with similar equipment.

Vipermax - Can I take it that the photos show the motor jacked up? You should be able to get the boat stable with the engine jacked up - at worst it will cause problems with acceleration and cornering, the height of the powerhead will obviously not help but if you can get the prop to bite rather than slip then it shouldn't be the cause of your problems - being able to drive the boat would help assess what the issues are. I am more concerned by the heavy steering - at what trim levels does this occur? If it is still occurring when the motor is trimmed out then I would address this first once again by changing the prop - it's easier than cutting out your transom!

I don't have static photos showing my engine heights for the race boat, but it was stable at over 90mph jacked up as high as it would go!

[Vipermax]

Originally Posted by Cookee

I raced against a 200HO with an XR2 (barely 195hp) so I did my homework and I also raced XS's

Vipermax - Can I take it that the photos show the motor jacked up? You should be able to get the boat stable with the engine jacked up - at worst it will cause problems with acceleration and cornering, the height of the powerhead will obviously not help but if you can get the prop to bite rather than slip then it shouldn't be the cause of your problems - being able to drive the boat would help assess what the issues are. I am more concerned by the heavy steering - at what trim levels does this occur? If it is still occurring when the motor is trimmed out then I would address this first once again by changing the prop - it's easier than cutting out your transom!

I don't have static photos showing my engine heights for the race boat, but it was stable at over 90mph jacked up as high as it would go!

Thanks for your concerned cookee.

Yes on the picture the jack is in up position. But not at the maximum height I think.
Concerning the prop I have been looking everywhere for tempest plus 25 or 26 in LH but I can't find any. So I think I will go for a Rev 4 25 lh which has got the same diameter as the tempest plus. What do you think ?

Then concerning the hard steering is has occured only with Bravo 1 26 and 28 and Maximus 26 ( I have not try other pitch). So I think it comes from the diameter of the prop which are bigger than tempest (no steering pb with the tempest 23).

Finally the boat is stable at top speed at WOT no pb. It is going side to side only when I reduce speed. And to avoid this effect I have to put the throttle back on.
But it is important to notice that the top speed is reached with the jack at only 2-2,5cm of height (so with the engine at 10-10,5cm above the hull).

I think I may (as said Oliver) lower the engine by 1 hole on the transom and then use more my jack to compensate the lost height. What do you think ?

Thanks.

Vipermax.

[Cookee]

Have you tried lowering the engine on the jack before reducing the throttle? If you lower the engine one bolt hole it will be that much lower at its lowest position which may help.

You don't mention the trim levels at which the steering becomes heavy?

Not familiar with the Rev 4 - is that a four blade like the Bravo?

[Mollers]

Originally Posted by Cookee

I raced against a 200HO with an XR2 (barely 195hp) so I did my homework and I also raced XS's

....and?

[Vipermax]

Originally Posted by Cookee

Have you tried lowering the engine on the jack before reducing the throttle? If you lower the engine one bolt hole it will be that much lower at its lowest position which may help.

You don't mention the trim levels at which the steering becomes heavy?

Not familiar with the Rev 4 - is that a four blade like the Bravo?

Yeah I have tried to reduce the height first but the phenomea still here.

For the trim:
- With the bavo it started at 1.7 and at 2.O and more the boat is totally undriveable
- With maximus it started at 1.9 and at 2.1 and more the main big issue.

Yes the REV 4 is four blade like the bravo 1 but in a smaller diameter 14-5/8 against
15-1/4 for the Bravo 1 and 15-5/8 for the Maximus (5 blade).

[Richard Selman]

Never raced but spent a lot of time thinking about what is going on back there.

I am getting 49 knots with one up + a full tank of fuel. I have the engine offset by 30mm + 90 kg me + 50 kg aux + 30 litre aux tank all on the right - medium battery on the left which cancels out the aux tank. I had to move the aux from the left to the right to get the balance right - she was OK in the water but tended to screw to left when leaving the water. When there is a second bod on the boat she starts to fall to the left again a bit however I tend to keep it in the water when there are others on the boat so prefer it is optimised for one up.

The planing pad on mine is 1250 mm long x 300 mm wide at the back and looks like it rises by 70 mm or 3.2 degrees. One point to consider is that because of the planing pad, your effective engine height (for comparing against set-ups without a planing pad) must be a bit higher that what you are measuring - i.e. the water right under the planing pad is less deep and also less clean due to being bent round the point of the pad than it would be with a conventional vee hull ending 70 mm lower. This would lead me to think that all other things being equal it would be better to have the engine a little lower relative to the edge of the planing pad than you would have for a normal vee.

For the planing pad to do any good I would have thought you must have to trim out a good bit to make it approach the horizontal. 3.2 degrees does not sound much but if you crouch under the boat as I have just done you can see how far the nose would have to come up to move it towards the horizontal. As you would start to trim out to make it sit on the pad you would start to lose the longditudinal stability of the keel. Also you then have to consider the sides of the planing pads that are about 7 degrees to the keel. I would have thought that if it were sitting on the pad and the boat turned to one side (due to steering or wave action), the back of the keel just in front of the pad and the deeper edge of the pad would tend might tend to steer the boat in the direction of the turn - perhaps there is a point at the speeds you are running that it becomes unstable.

Mine is rock steady laterally at WOT however as you trim out to sit on the pad to creep the speed up to the max you can definately feel the boat starting to slip sideways slightly and the steering getting heavier - you have to run with the steering very slightly offset to compensate. Its weird at first but now I am used to it. Only appears in the last 5 knots or so perhaps it gets more significant at your speeds.

I tend to not put it into a hard turn at those speeds so have yet to find out what happens. It has never shown any signs of instability at any moderate turn at speed or a hard turn at any lower speed.

You can bank the boat up at an amazing angle if you want to - perhaps the higher tube fixing permits this. I have always found it self limiting - once it goes past the 45 degree point the prop will surface and there will be no more force to heel the boat any further over. My favorite party piece at the end of a spin is to bank her hard over and then put her into a sideways slide. Always wondered what would happen if I suddenly reversed the steering and let the keel or skeg sudden bite the water though......

Richard

[PeterM]

Originally Posted by Richard Selman

My favorite party piece at the end of a spin is to bank her hard over and then put her into a sideways slide. Always wondered what would happen if I suddenly reversed the steering and let the keel or skeg sudden bite the water though......

Richard

Or a wave came up a little ? I'd guess you and the boat part company as you smartly leave on the outside of the turn ?? I hate 'sliding' a boat like that - its a huge amount of risk ......( but great fun )

The Shearwater just would not do it no matter what I did - the Avon.... all over the place !

[Vipermax]

[QUOTE=Richard Selman;384137] Never raced but spent a lot of time thinking about what is going on back there.

The planing pad on mine is 1250 mm long x 300 mm wide at the back and looks like it rises by 70 mm or 3.2 degrees. One point to consider is that because of the planing pad, your effective engine height (for comparing against set-ups without a planing pad) must be a bit higher that what you are measuring - i.e. the water right under the planing pad is less deep and also less clean due to being bent round the point of the pad than it would be with a conventional vee hull ending 70 mm lower. This would lead me to think that all other things being equal it would be better to have the engine a little lower relative to the edge of the planing pad than you would have for a normal vee.


First, thanks for your reply.

I wonder when was build your boat ? Because I wonder if we have got the same pad dimension or not.
Then that is the longer of your shaft and how high is your engine ?

Have you check the the hull and rule it in or out ? In order to see if it is perfectly flat ? Because I suspect mine to have a mould defect.

Thanks.

Regards.

Jean-Charles.

[Richard Selman]

The hull is just over 3 years old - built around Oct 2007

Fully trimmed in, the anti-ventilation plate projects to 45mm above the bottom of the transom (trailing edge of the planing pad).

The engine is a Yam F250 ultra long shaft. Just hanging on the transom cutout as normal and bolted straight on with no mods made to the transom.

Peter - would only skid the boat in calm waters - would not want to go over a wave sideways! Takes a lot of effort to make it do it. Won't do it by itself if the power is on no matter how hard the turn I think.

Richard

[Richard Selman]

.....don't see any significant issues with my hull strakes (virure) - I would not have thought that little differences of of the size you seem to have would be the problem.

I am using a Yam 14.5"D x 23"P ported stainless prop. Only problem so far is that if I have not been out a while I tend to forget that it sounds funny at low revs so I often lift the eng to check the prop for seaweed. Not so good for tight manouvering work though (especially in reverse) since it is spinning in bubbles. If I am on rescue duty at the sailing club I will change it back to the 21P stainless or 23P aluminium normal ones I have.

There was a post on here a while back that compared various props for a 7m boat. This one came out the best. Too far north to get access to test props and there was only one boat in the area with anything like this size of engine to borrow a prop but he was running a lower pitch prop for a heavy 8m sea-safari rigged humber so just bought this one and stopped worrying about it.

Richard