Outboard height too low. Run out of adjustment.

[Rip it up]

Hey guys.

Recently repowered a cruisecraft rogue 14ft. With a 2004 80hp Yamaha.

Going through the gremlin stage.

http://tapatalk.imageshack.com/v2/14/11/07/a027b8e983f07f78c22fec24abc96835.jpg

This is the 3rd hole setting against the keel.

A good 60mm below where it should be.

The boat is behaving poorly at this setup.
Porpoising, chine walking at WOT. Massive bow lift.

Now I swapped this motor from a 60hp Yamaha due to a nose heavy issue with two POB. And punching into larger swells was uncomfortable in Gladstone Harbour.

Now it seems I've gone the other way. I will be changing some weight around in the boat to combat this.

I currently hold 90L of fuel in two stainless cruise tanks in each corner. I will drop back to the larger one only. Move some gear up under the nose and possibly add a heavy anchor as well to counteract the massive weight change of the 80.

It has a drill free se300 foil which should not change the handling too much at planning speeds but might be causing some of the gremlins.

A few water test drums are needed.


But how do I lift this outboard further up without any more holes on the bracket? How can a 20" leg be different from model to model? These mounting holes are the original cruisecraft bolt pattern from 1976. So maybe there was a change at some stage to a higher pattern.

Can anybody help?
I'll still new holes if need be. Be its a little strange.


Damo's dodgy boat building factory.

[Moonlighter]

With the foil you have fitted there being under water when the boat is underway, I suspect it will make a bad situation, worse. So first thing I would take that off.

if you are going to keep that motor, it definitely looks like it is a fair bit too deep, and the symptoms you describe tend to confirm exactly that. The only final confirmation would be to check the cav plate when the boat is planing, it should be skimming the surface, buI am betting it is buried a good way inder the water.

The engine needs to be lifted, one way or another. By a decent amount, too. Do you have room above the existing top bolt holes to put in a new set a couple of inches higher?

[scottar]

Jacking plate or a heavy alloy plate would be the easiest.

[Rip it up]

Hey moonlighter.

The hard part of taking photographs of the cav plate is the movement of passenger weight affects the trim so much in a 14fter.

Need a go pro!

The foil being buried heavily does make me think it will be affecting my small trim angles.

The thought process goes like this. Foil has enough surface area to lift the weight of boat at WOT. And with the motor being too low it forces the boat to chine walk because of the minimal boat in the water trying to overcome the water drag.

Off it comes tomorrow.

But will my bow up attitude when getting out of the hole be better or worse with it off?

Water testing required I think.


Damo's dodgy boat building factory.

[Rip it up]

Scotty, i have a composite transom material that is not affected by water ingress. So I can drill as many holes as I like in the transom.

So I think I will test the higher holes to start with and see if it makes a difference to the porpoising.


Damo's dodgy boat building factory.

[Moonlighter]

I would take the foil off and put the motor up to the highest possible position you can get it on the existing bolt holes, and test again. A buried foil is bad from all sorts of angles. You may still have to get the motor higher. Engine buried too deep throws angles of thrust out and hull behaves badly and somewhat irrationally. Engine height a pretty important factor, especially when it is a long way out.

Relatively small boat, older style hull not designed to take weight of quite heavy, large 4 stroke motor on the bum, compounds the issue. A bit surprised that 60hp motor didnt perform quite well on the 14 footer???

Many years ago a mate of mine had a Haines 146C, originally had a 55Johnno on it, blew that up and went to a 70 Yammy 2 stroke, the thing was a rocket ship with that 70, at WOT it was barely touching the water. Scary. I also remember aboat magazine test of an Alison 16 footer where the boat performed terribly and was lambasted by the tester, much to the disgust of the manufacturer. It all came down to a badly rigged engine, set far to low, they re-rigged it and it transformed the boat's performance and handling and whole attitude.

The chine walking at WOT may simply be that you are pushing the limits of the hull at that speed and with that foil making weird things happen. It could also be that the boat/motor combo is just not one that is going to go all that well together, even when you have the engine set to optimum height.

Good luck with sorting it out, starting with a clean sheet by getting that foil off and lifting the motor to the optimum position is the best approach, i think. Then work from there.

[scottar]

At a guess with the foil removed you will pick up some extra rpm and possibly top end as well but will lose the ability for slow speed planning to an extent. It may be a set of tabs might be a better option as I found on my rig.

[cwcarter]

Those drill free kits are the worst things going. Look how chunky they are!!! If anything remove that if your keeping the foil. But as said try everything else first with the foil removed.

[Noelm]

A picture of the motor mounting would be nice, it is not an XL (25") motor by chance is it? Oh, and get the foil off ASAP.

[docaster]

And a pic with outboard anti-cav plate level with the hull from behind.

[Rip it up]

http://tapatalk.imageshack.com/v2/14/11/09/2d779a28d39c79f71cb5e0a2f2f0ea94.jpghttp://tapatalk.imageshack.com/v2/14/11/09/0d64554514dcd940b984379b4d8f2628.jpghttp://tapatalk.imageshack.com/v2/14/11/09/daefd7d0de53dd0ccd51d68ef6fe3554.jpghttp://tapatalk.imageshack.com/v2/14/11/09/40df8bacdef5b82406ef407f9097cd63.jpghttp://tapatalk.imageshack.com/v2/14/11/09/ba742c3cd3136ab8317fa919590a10f7.jpg

Any suggestions.

I'm thinking some sort of aluminium jacking plate.


Damo's dodgy boat building factory.

[Rip it up]

Measures the same as the 60hp. 20".


Damo's dodgy boat building factory.

[mustang5]

The Haines I purchased for a project boat came with one of these.

I had to chop it up to get it off, otherwise Id throw it your way.

All it was is 2 6mm bits of flat welded and boxed off in the extension part. That was holding 200hp.

[Rip it up]

I had a thought to use aluminium PFC. http://tapatalk.imageshack.com/v2/14/11/09/f7938661cb1924de9c3c50aa7f4012dd.jpg


Damo's dodgy boat building factory.

[mustang5]

I used to own a 5m Mustang with a 90hp Yamaha hanging off one of those. I think they serve the purpose.

[Rip it up]

Thanks mustang. I'll looking into some DIY options.


Damo's dodgy boat building factory.

[mustang5]

10mm C Channel x 2 and a good Drill bit should do it.

[Rip it up]

Yeah need to find some that sells it by the meter. Not much point buying 6m of it.


Damo's dodgy boat building factory.

[odes20]

Why not drill new holes ?? you seem to have plenty left at the top of the transom?
I would be seeking to minimise moving the weight any further back as well, as that is a a bit counter productive IMO.

Also are you saying you have 90 litre fuel capacity in stern as well. I would be getting that out of there as well, that's a lot of weight in the wrong part of the boat, isn't it?

[Rip it up]

Thanks odes.

I'm considering the drilling of new hole. But due to my construction methods of the transom I would need to do a fair bit of fibreglass reinforcing to make that happen.

My transom is built from plastic honeycomb and epoxy resin. Where the original bolt holes are there is a 2" solid plug to bolt through so the bolt do not compress the honeycomb.

Whilst my transom will never rot. It does require some special mounting treatment.

So a little bit of extra work to move the holes. http://tapatalk.imageshack.com/v2/14/11/10/cb7725c0ceaa518265614d5fa89c26e6.jpg
The white dots are visible in this photo.


Damo's dodgy boat building factory.

[odes20]

OK now I can see why you are seeing as a last option Ha!

Cheers!

[aussiebasser]

The Alloy channels you posted would work. Just remember, as you go back, you have to go higher as well, so you'll need to raise the motor more than you think. Can you buy Aluminium in Gladstone?

[Fed]

If it's to sell I'd put the 60 back on and sort it out then keep the 80 for another project.

[JB sniper]

Rip it up I have a manual adjustable jacking plate that could help you out. I live in boyne. I Only used for two months then redid transome and repowered so drilled new holes and have no need for it. If you pm me and are interested we could work something out maybe try it and if you like it you could buy it off me.

[Rip it up]

Yes we have a specialist aluminium shop in town.

The 60hp outboard was swapped for the 80hp in a trade deal. So no longer an option

The boat is a well utilized communal boat for family and friends, which will not be sold for a long time. It was upgraded to the 80hp for wakeboard and watersports. And does that job very well.

The benefit to the stern heavy nature is the bow does not bury into waves with two passengers anymore.

I just need to fine tune the install for performance.




Damo's dodgy boat building factory.

[aussiebasser]

JB's Jack Plate will do the job for you. Once you have the height adjusted, stick a deflated basketball into the jackplate and pump it up. That will give you the flotation you need in the back.