Is this propeller angle right?

[lqbweb]

Hello,

I am starting building a boat. 26'' Mono Hull (640mm), and I am trying to get the propeller angle right at 75mm.

Does this propeller angle look like too much? It is basically on the keel line. I can't make it more flat if it is not by lifting the shaft a bit at the hole (making the hole bigger at the top), as there is not enough room in the hull for the motor to rest lower. Should I do it? There is around 4.5mm from the bottom of the hole to the keel.

Thanks a lot!

[Jesse J]

What hull is this? Do you plan to use a strut?

[Fluid]

Is that a solid prop shaft or flex? What does the OP mean by a 75 mm prop angle?

There are two adjustments preferred for the prop shaft, angle and depth. A solid shaft has neither, it should be installed as designed. What does the hull maker recommend?


.

[lqbweb]

Is that a solid prop shaft or flex? What does the OP mean by a 75 mm prop angle?

There are two adjustments preferred for the prop shaft, angle and depth. A solid shaft has neither, it should be installed as designed. What does the hull maker recommend?


.

yes, this is a solid shaft. By 75mm I meant the depth from the transom to the end of the shaft (where the bearing is). This is around 12% of the total length (which I believe is the recommended value).

The hull is an Hydro Marine Firebee:

https://www.hydromarine.de/Hulls/Mono-Hull-Boats/Mono-Ruempfe-bis-700-mm/FireBee-the-new-Eco-Package-Price-Offer::1957.html?language=en

I have tried already to contact them, but I received no answer so far. Only info available is a link there from a similar setup:

http://hydromarine.magix.net/alle-alben/!/oa/7413266/

I am trying to leave around 2mm from the bottom of the bearing at the end of the shaft to the surface where the boat is resting.

Thanks a lot!

[Jesse J]

Are you setting this up a
For eco or mono 1 or just sporting?
Check with nativepaul, he is pretty plugged into those enduro/eco classes and setups.

[lqbweb]

Are you setting this up a
For eco or mono 1 or just sporting?
Check with nativepaul, he is pretty plugged into those enduro/eco classes and setups.

It is just for sporting and fun, not planning to compete anywhere. I will contact him, thanks :)

[NativePaul]

Thanks but this is well out of my comfort zone I am a cat and hydro guy I only have 2 monos and 1.5 Ecos, both my monos are stepped and built old school with flexies and struts.

Current boats use fairly long straight wire drives with center bearings, to place the motor down in the step and the prop hub slightly above the table, about 1.5mm i think. this small loss of efficiency from the down thrust is countered by being able to move the CoG back a little we start at 28% rather than the more common 30% and the lighter drive saves weight, which helps efficiency too. Low lift props are a requirement, Octuras won't work, everyone is using CNC props with low blade area shapes based off the Graupner carbons. TP are alloy Graupner clones, Tenshock are modded alloy Graupners and slightly better, Dr Props have gone their own way but you can see the Graupner influence.

Don't expect to get it right first time, I know experianced Mono racers that hot glue in the shaft on first build with a new hull, and only glue it in properly after testing.

The motor size and cooling can matters, everyone uses long 28/29mm motors rather than short 36mm motors, to bring the shaft down low. There is a difference in the OD of cooling cans too, Lehner, TP or TFL are all on the slim side whereas a leopard and some generic coolers would put the shaft 1 mm or more higher, not sure if HRC make cans in this size or not, but they are really fat and would raise it up at least a couple of mm. Where you place the can makes a difference too, if the can isn't full length, slide it to the back and you can get the angle a little lower.

This looks like a fun running setup to me, an Eco ish hull, but Ecos are submerged drive so that would be out, and I can't imagine a flat bottomed unstepped mono being competitive in the mono classes. I do know a couple of people that have put surface drives on Ecos and it can make a very fun boat.

[lqbweb]

Thanks but this is well out of my comfort zone I am a cat and hydro guy I only have 2 monos and 1.5 Ecos, both my monos are stepped and built old school with flexies and struts.

Current boats use fairly long straight wire drives with center bearings, to place the motor down in the step and the prop hub slightly above the table, about 1.5mm i think. this small loss of efficiency from the down thrust is countered by being able to move the CoG back a little we start at 28% rather than the more common 30% and the lighter drive saves weight, which helps efficiency too. Low lift props are a requirement, Octuras won't work, everyone is using CNC props with low blade area shapes based off the Graupner carbons. TP are alloy Graupner clones, Tenshock are modded alloy Graupners and slightly better, Dr Props have gone their own way but you can see the Graupner influence.

Don't expect to get it right first time, I know experianced Mono racers that hot glue in the shaft on first build with a new hull, and only glue it in properly after testing.

The motor size and cooling can matters, everyone uses long 28/29mm motors rather than short 36mm motors, to bring the shaft down low. There is a difference in the OD of cooling cans too, Lehner, TP or TFL are all on the slim side whereas a leopard and some generic coolers would put the shaft 1 mm or more higher, not sure if HRC make cans in this size or not, but they are really fat and would raise it up at least a couple of mm. Where you place the can makes a difference too, if the can isn't full length, slide it to the back and you can get the angle a little lower.

This looks like a fun running setup to me, an Eco ish hull, but Ecos are submerged drive so that would be out, and I can't imagine a flat bottomed unstepped mono being competitive in the mono classes. I do know a couple of people that have put surface drives on Ecos and it can make a very fun boat.

Thanks man! Considering it is not your area of comfort, you are very much aware of the complications that I am actually having hahaha.

I am fitting a Leopard 3650, since that one was the recommended one by Hydro Marine. Yes, maybe a 28mm would have have been better and more conservative, an yes the cooler is not helping here. This is mine:

https://www.rc-raceboats-shop.de/lng/en/water-cooling/wasserkuehlmantel-fuer-36mm-motoren-40mm-lang-.html

I have also added a a foamy layer underneath, another 1mm, so the motor is not in touch with the hull. I wanted to avoid transmitting vibrations to the hull, but maybe I am paranoid here.

All and all, I think I am slowly getting it right. I have made the hole 1 mm higher on the top, I think I am reaching 2mm clearance to the table now, with a fairly straight angle. I will hot glue it first, this was a good advise.

Any trick on how to make sure the shaft is coming out horizontally straight (same distance to the propeller from both sides), or also try and adjust?

Thanks!

[Jesse J]

Paul, do you have some recommendations for 28/29 mm motor brands? I’m also fussing with a mono2 that needs a redo.

[NativePaul]

Tenshock are probably the most popular mono1 motors their Viper and Evo ranges are both good depending on your budget, next most popular are leopard (not as good but cheaper), Lehner, ETTI (are probably next in popularity but I don't rate them highly), TP, then the odd random Chinese motor, Mega, Neu, Kontronic. Drmadthrust were pretty popular, but I think are no longer available. My personal Mono1 has a Leopard 2860 3400kv on 3s.

A Mono2 needs a 36mm motor, popular brands are Leopard, Tenshock (CZ range instead of Viper and Evo), Lehner, TP, HK (purple), Gool RC, ETTI (again I don't rate them highly). I don't have a Mono2, but if I did it would probably have a purple Hobbyking 3674 1650kv on 6s.

[lqbweb]

Ey guys, today I have loaded it up with what it will be the final setup. How do you see it? It is completely submerged. I did not expect the transom so deep in the water. Will it be alright? I am still waiting for the ESC to arrive so I can't really test it yet (but I have simulated the weight of the ESC for the photos).

I will try to increase the angle of the rudder arm a bit. It is completely sunk in the water. It out does not matter?

It should lift up a bit while running fast right?

Thanks

IMG20200628152556.jpgIMG20200628153250.jpgIMG20200628152455.jpg

[Jesse J]

Um, so I’m sure you are talking about “up on plane” depths..
to me, if the second pic is flat on the hull bottom, it should be a good place to start.

[lqbweb]

Um, so I?m sure you are talking about ?up on plane? depths..
to me, if the second pic is flat on the hull bottom, it should be a good place to start.

hahaha yes, looks like that is the proper term. Sorry I am a bit newbie in this.

So, when it is up on plane, at what height should I expect it to be floating on at what speed? what is your experience so far?

Thanks for all the help, is very much welcome.

[lqbweb]

Guys, is this correct? There has to be a bit of clearance there right? The propeller does not go any more in, it does not matter right?

[Jesse J]

Is this a wire drive or flex? If flex, then not enough space. If wire, then this is minimum.
Space in front of prop is not problem.