Engine jack plates

[codprawn]

It could be because you have a stepped hull - they like to run flat.

Also prop choice may have something to do with it. Often they run cleaver type props when the engine is high up.

[Jorgos]

I use a 'cyclone' propeller 4blade and pitch 23'

[Cookee]

It depends on the prop and gearbox and how high you take the engine - you need a low water pickup to get the engine high enough to make a real difference- you also have to factor in that you have moved the engine back, so you can in theory lift it higher the further back you move it.

There are a great number of factors here, and the other thing to bear in mind is that you lose bow lift the higher you raise the engine, you may then need a prop with more bow lift on it to make the best use of the new setup ......... it's complicated!

[Jorgos]

you are right it is complicated.
The boat has already a build in bracket that is not touches the water. The trim was just a bit higher than the lower position (10%) the gear reduction is 1:85.
( so far before i fitted the power lift I had 55+ knots from this propeller at 5450 rpm)

Could you please explain that?

you need a low water pickup to get the engine high enough to make a real difference-

[Cookee]

On gearboxes like the Mercury race boxes the water intake is on the bottom of the nose of the gearbox which allows you to raise the engine without losing water pressure, with the normal intakes on the side of the gearbox they limit the height you can get an engine up to reduce drag.

Fuel consumption would only improve if you raise the engine up high and then throttle back to keep the boat speed the same - if you keep it at wide open throttle, the boat will go faster with more RPM, and may even increase fuel consumption, but you will be going faster!

[Jorgos]

Thank you.
When I will try it again I will post my news.
3 blade or 4 blade suit better the power lift?

[Cookee]

Originally Posted by Jorgos

Thank you.
When I will try it again I will post my news.
3 blade or 4 blade suit better the power lift?

It's more a question of what suits the hull - 3 or 4 blades both work with a lifter ..........

[Bigmuz7]

Originally Posted by codprawn

Often they run cleaver type props when the engine is high up.

My Verado was set very high, (which is its correct fitting position) but I was surprised that the standard recommended prop had a relatively normal cupping on it, I experimented with a 4 bladers too and improved certain characteristics, but lost others

[Cookee]

Originally Posted by Bigmuz7

My Verado was set very high, (which is its correct fitting position) but I was surprised that the standard recommended prop had a relatively normal cupping on it, I experimented with a 4 bladers too and improved certain characteristics, but lost others

Yes Verados do like to be run high on the transom - our 770 with a 250 ran 64mph and was quite high up on recommendation from Barrus.

Codprawn - Cleavers are run on boats because the hull likes the characteristics of those props, not only because they are high or running a lifter.

My opinion is that the only time to fit a lifter is for racing or when you regularly run in shallow water - pointless for regular leisure use ...............

[Jorgos]

I tried once but i did not ha the chance to see the top speed.
I got an increase on cruising speed ( in good weather) from 38,5 to 40 knots at 4000 rpm and 1liter per mile with the engine low

I will try again this weekend

[Ezgoing]

Hi guys

Just wondering if any of you have any updates on your experience with jackplates, new models, usage reports etc

thks

[Steven@BMS]

Originally Posted by Ezgoing

Hi guys

Just wondering if any of you have any updates on your experience with jackplates, new models, usage reports etc

thks

Hello from Bob's Machine Shop. We are the company that produced the jack plate on Robbie Diesels boat (post 9).

I just wanted to update you guys on some of our new jack plates, and explain some of the features/benefits of our jack plates.

We now have 3 lines of jack plates, Mini (1 - 50HP), Standard (50 - 300HP), and Extreme (350+HP including V8s)

We are currently developing a new 14 inch setback standard jack plate.

Unlike other brands of jack plates, we do not put the hydraulic pump inside the structure of the jack plate, but have it remotely installed inside the boat. By keeping the pump out of the elements it gives a long, trouble free life. Also since the pump is not as size restricted it is much stronger, and gives a faster lift time than other brands.

We give a lifetime warranty on the structure of the jack plates, and a 3 year warranty on the hydraulic pump.

Also in the April 2009 issue of TrailerBoats magazine, they did a test on 3 different style boats to see gains of our jack plates. If interested in having me send a digital copy of it, please email me at info@bobsmachine.com or you can check it out on our facebook page www.facebook.com/bobsmachineshop

You can also check out our youtube channel www.youtube.com/bobsmachine One of the videos is of ribs with 350HP Verados that I think you guys would like

Thanks for reading my spiel, best regards,

Steven

[Cookee]

Originally Posted by Steven@BMS

Hello from Bob's Machine Shop. We are the company that produced the jack plate on Robbie Diesels boat (post 9).


Unlike other brands of jack plates, we do not put the hydraulic pump inside the structure of the jack plate, but have it remotely installed inside the boat. By keeping the pump out of the elements it gives a long, trouble free life. Also since the pump is not as size restricted it is much stronger, and gives a faster lift time than other brands.

Thanks for reading my spiel, best regards,

Steven

I would add that the Stainless Marine jack plates also have the pump on the inside of the boat as well.

[Zubenelgenubi]

Is a jackplate adjustable in the up & down plane while the boat is on the move or do you just find the correct height setting & set it at whatever that setting is?

I have an XLS outboard (25" leg), if I was to transplant it to another boat with a 20" transom could a jackplate be used to raise it up to make it suitable for a 20" transom or is the cost of the jackplate prohibitive & would it be more effective to just raise the engine up by clamping it to the transom as high as possible using the lowest of the upper holes on the engine mounting bracket? Would this method cause undue stress on the engine bracket?

[Steven@BMS]

Originally Posted by Zubenelgenubi

Is a jackplate adjustable in the up & down plane while the boat is on the move or do you just find the correct height setting & set it at whatever that setting is?

I have an XLS outboard (25" leg), if I was to transplant it to another boat with a 20" transom could a jackplate be used to raise it up to make it suitable for a 20" transom or is the cost of the jackplate prohibitive & would it be more effective to just raise the engine up by clamping it to the transom as high as possible using the lowest of the upper holes on the engine mounting bracket? Would this method cause undue stress on the engine bracket?

Our jack plates can be raised and lowered while the engine is running at full power (hydraulic models that is)

The manual units are able to be adjusted, but normally once you find the 'sweet spot' they are left alone.

Many people use jack plates to correct exactly the same problem you have. The best option for this is the smallest setback possible (4 inch in hydraulic models, 2.5 inch in manual) This is because the further back you go, the more the water uncompresses from under the hull and lifts up. So if you go too far back, it will negate the corrections the jack is making. As a rule of thumb, every 2 inches of setback you go, you can run the engine 1 inch higher on the jack plate (obliviously not the same for all boats, but roughly).

Our Hydraulic and Versa manuals have 7.5 inches of lift

Our convertible manual jacks have 6.5 inches of lift

[Zubenelgenubi]

Excellent info! So basically I would need a manual unit with a 2.5” setback?
That way I could by trial & error find a sweet spot. How much adjustment is there vertically on the jackplate? I guess the initial location of the fixed mounting on the transom is important at the outset.
Do you have a website?

[Steven@BMS]

Originally Posted by Zubenelgenubi

Excellent info! So basically I would need a manual unit with a 2.5” setback?
That way I could by trial & error find a sweet spot. How much adjustment is there vertically on the jackplate? I guess the initial location of the fixed mounting on the transom is important at the outset.
Do you have a website?

In our convertible manual there is 2.5 inches of lift built into the structure, then an additional 4 inches of adjustable lift.

Regarding mounting, the unit is a standard BIA bolt pattern, so it will just mount in the stock engine location. No need to drill new holes

Our website is www.bobsmachine.com

email : info@bobsmachine.com

[Poly]

Steven its always good to see component manufacturers participating in the forum discussions, especially when they are able to provide some insight into some advanced features like this -- however its also worth bearing in mind that any "commercial" posts fall within the forum's trade membership rules.

[Steven@BMS]

Originally Posted by Polwart

Steven its always good to see component manufacturers participating in the forum discussions, especially when they are able to provide some insight into some advanced features like this -- however its also worth bearing in mind that any "commercial" posts fall within the forum's trade membership rules.

I sent an email to the administrator requesting advertising info

I already can tell this is a great forum and am happy to work as a sponsor here.

[Poly]

Originally Posted by Steven@BMS

I sent an email to the administrator requesting advertising info

I already can tell this is a great forum and am happy to work as a sponsor here.