Bow Dropping & Prop Ventilation

[Excelent]

Hi,

Recently bought an Excel Volante 390 with a 9.9 outboard. First powered watercraft I’ve ever had.
Had it out on the river Trent yesterday to text and got it up onto the plane easy enough but the problem is that when on the plane and speed increasing, the bow seems to drop lower and lower until suddenly it feels like the prop pops out and the boat drops off the plane.
What am I doing wrong?
Had a bit of a play and worked out that once on the plane if I backed off the throttle a bit before the bow dipped too much it’d sit nicely. Obviously I’m then not using full throttle. Be nice to go flat out!
Any advice would be appreciated.

Cheers

[Fenlander]

Hi and welcome to the forum.

First as always are all the sections fully up to pressure with a gauge you trust to be accurate? Have you rechecked after a few mins on the water to offset the cooling effect?

Is your load (people/kit/fuel tank) well placed to trim the boat level? Where is the outboard trim pin position?

Is this an air floor model with the flat grey air cushion floor?

[pumpkinking]

Originally Posted by Excelent

Hi,



Recently bought an Excel Volante 390 with a 9.9 outboard. First powered watercraft I’ve ever had.

Had it out on the river Trent yesterday to text and got it up onto the plane easy enough but the problem is that when on the plane and speed increasing, the bow seems to drop lower and lower until suddenly it feels like the prop pops out and the boat drops off the plane.

What am I doing wrong?

Had a bit of a play and worked out that once on the plane if I backed off the throttle a bit before the bow dipped too much it’d sit nicely. Obviously I’m then not using full throttle. Be nice to go flat out!

Any advice would be appreciated.



Cheers

Strikes me that your outboard trim pin might be set too far in, as Fenlander says.

When the boat is floating still in the water is the leg of the outboard pretty much angled vertically down into the water, or is it angled in towards the transom or out away from the transom?

[Excelent]

Hi,

The leg seems to be fairly vertical with the transom. I did try setting the trim pin to hole 2 but not much difference I don’t think.
It’s almost as though the leg/prop could do with sitting a touch lower in the water.

[Excelent]

Hi,

I do need to get an electric pump but I was using my manual SUP pump which I’ve cross checked with other pumps previously and was accurate.

Yes, the Volante has the 10psi soft deck with the plastic inserts underneath. This was solid.

Tried hole 1 and 2 but the boat still wanted to drop the bow and lift the prop out the water when planing and accelerating.
As previously mentioned, if I backed off the throttle and got the right speed to keep the bow from dipping too far it sit on the plane nicely but as soon as I gave it any more throttle the bow would dip down and the prop wound pop out.

[Fenlander]

When you talk of hole 2 on the OB pin how many holes does it have and is this second from nearest to transom or second from as far lifted up as it will go. And if you tried 2 which position were you using otherwise?

When you say the leg was vertical with the transom do you mean parallel with the transom? I ask because all transoms lean back at the top so if an outboard is trimmed parallel to it then that would lift the prop and push the bow down.

Also is the outboard (make?) used or new... if used could it be fitted with an odd aftermarket prop?

[Excelent]

There’s 4 holes, 1st being closest to the transom and 4th being most angled away.
I tried 1st and 2nd.
I think at hole 1 the leg sits pretty much plumb as there’s a wedge on the outboard to compensate for the transom angle.

Outboard is a low hour Yamaha/Vector 9.9. It’s practically new and looks unlikely to have had an aftermarket prop on it.

So, where do I need the trim angle?

[charliee]

Where did you sit and did you have much kit on board - where was your fuel located?
It sounds like you have too much weight towards the bow?

[Fenlander]

Any photo of the "wedge" to compensate for the transom angle... not ever seen that.

[Excelent]

See image

[Excelent]

Struggled for a minute there but the profile on the clamp “wedge” means when the leg is set at hole 1, it’s most Inward setting, it sits pretty much plumb.

[Excelent]

Tank upfront. Wife and 5yo towards the middle. No kit as such. Just a small bag with a few tools and snacks in at the back with me.
I’ll experiment with getting the wife and daughter towards the back next time.

[TmMorris]

It's a strange one. I have the same boat with a 15 on it and it behaved perfectly from the get go with the outboard sat on the the transom and no trim applied. Whether with any passengers up front or solo it pops up onto the plane and the bow, at all times, is doing as expected.

The only thing that I can think of is that it isn't as inflated as you think it is as the hull must be flexing under the application of peak torque/power?

[Fenlander]

Am I missing something... I really can't see any wedge in that image.

[Excelent]

I might be wrong but it doesn’t feel like a flex. It feels more like the boat climbs onto the plane but then doesn’t settle there unless you back of the throttle slightly. If I back off the throttle, it sits really nicely but If I continue to wind the throttle open the bow slowly drops and in turn the stern slowly lifts to the point where the prop starts to crown out of the water, looses thrust and the boat drops back down.
My friend has the same boat too with a Suzuki 20 on it and has had the same issue.

Perhaps it’s as simple as keeping all the weight at the stern for more spirited journeys?

[Wazzajnr]

Hasn't got a doel fin fitted has it? Thinking too much lift at the stern possibly?
It's a weird one as virtually every other sib question is how do I get the nose down. You seem to have the opposite issue to most people!

[Steve509926]

There's no wedge David, it's a standard transom clamp.
Two things come to mind, 1st is pressure - if it's the standard Excel pump that came with the SIB the scale isn't the best, so I would say it's probably under pressure. I slightly over pressure my Excel, knowing that it will lose at least 5% as soon as it hits the water, then I will check it at the first stop.
2nd is the 9.9hp - has it got enough to get it over the "hump"? It sounds very much to me as though it's not on the plane and then falling off, it's riding up a bow "wave" and hasn't got enough to get over it and then sit on the plane.

[jeffstevens763@g]

It’s a bubble of air escaping hitting the prop it loses grip and drops off the plain floor needs to be taught and weight distributed so the boat travels level it doesn’t need much to throw it out of balance.

[Fenlander]

>>>There's no wedge David, it's a standard transom clamp.

That was my thought... it was just the OP mentioned a "wedge on the outboard" to compensate for transom angle.

[Excelent]

Thanks. I have read this somewhere before. This is essentially what it feels like so I will get my pressures spot on next time and check after been in the water.
My explanation of the prop popping out the water was only an assumption based on what it felt like. Obviously I didn’t have a visual on this event happening but your explanation sounds like it could be the issue.
Was only my first time out so will no doubt be some time until I find the sweet spot on set up.