Schionning Arrow 1200 - Propulsion (Current Marine?)

[tp12]

A very good morning to you all.

I've been rewatching a few youtube videos recently and picked up something I'd missed before on one of them.

The video below, which is a build update on a number of boats in different areas, has a couple of Arrow 1200s being built in South Africa. I assume by Current Marine, given a recent conversation I've had, so I'm going to send them an email as well but thought I'd also ask the question here.

If you go to 5:53 in the video you can see the port hull of an Arrow with what appears to be a retractable drive leg of some description. I've taken a snip of it also (a small png) and attached it.

Does anyone know anything about it?

If not, I'll post up any reply I get from Current Marine as well. Here's the youtube vid:

https://www.youtube.com/watch?v=Q9N4NRsvK_g

[Dave_S]

It looks like a Yamaha 25hp high thrust. Might be smaller than 25 ?

[tp12]

Originally Posted by Dave_S

It looks like a Yamaha 25hp high thrust. Might be smaller than 25 ?

The Arrow 1200 design has one, centrally mounted outboard. So this looks like it's used the standard Schionning well, used in other designs and I think yours?, and chucked two in the hulls?

I must admit when was talking to Jeff and he mentioned using the one, central outboard and maybe bow thrusters I was a wee bit put off. The ability to oppose two engines has always appealed.

I was hoping this was some tricky retractable electric drive leg

[tp12]

I think I need to check my excitement ... they show they've added an outboard well later in the video ... ! Hahahaha Bugger.

This remains my dream propulsion - a retractable, electric drive leg. Where the motor lives; I'm open to options as I understand they may not need to be together. I shall keep looking ...

[Dave_S]

I'm sure they would make a submersible electric motor drives that would be suitable then its just a matter of lowering them into position on a slide or swing arm.

[BigBeakie]

TP,

Can't see why an Oceanvolt SD15 or Servoprop leg could not be mounted to be swing down. Jeff has some experience now with OV, so will have ideas, I'm sure.

Having said that, the drag from the OV legs is really minimal ( they are very slim), so what's the point? The Vendee Globe Imoca 60's just mount them normally.

Then you can have heaps of regen as you sail along, when you want. That far outweighs any perceived disadvantage of the minimal drag, IMO.

[tp12]

Originally Posted by BigBeakie

TP,

Can't see why an Oceanvolt SD15 or Servoprop leg could not be mounted to be swing down. Jeff has some experience now with OV, so will have ideas, I'm sure.

Having said that, the drag from the OV legs is really minimal ( they are very slim), so what's the point? The Vendee Globe Imoca 60's just mount them normally.

Then you can have heaps of regen as you sail along, when you want. That far outweighs any perceived disadvantage of the minimal drag, IMO.

Why not have both?

There's other advantages to being able to do it than just avoiding drag, though that's still worth doing IMO. For example, much less time sitting in salt water so won't barnacle up and the, relatively, minor cleaning can be done without jumping in. Same for fishing net/line/whatever tangles. Hitting a log/something else .... I think it's a very worthwhile thing to do that can save me a lot of hassle. I plan on kickup rudders for the same reason. You could lift your boards, engines/leg/whatever and rudder out of the water and present a smooth bum below.

Definitely worth another chat with Jeff.

[valhalla360]

Originally Posted by tp12

The Arrow 1200 design has one, centrally mounted outboard. So this looks like it's used the standard Schionning well, used in other designs and I think yours?, and chucked two in the hulls?

I must admit when was talking to Jeff and he mentioned using the one, central outboard and maybe bow thrusters I was a wee bit put off. The ability to oppose two engines has always appealed.

I was hoping this was some tricky retractable electric drive leg

Assuming the centrally mounted drive is steerable, you don't lose nearly as much as you might think. Yes, twins are still better but the ability to direct the thrust makes up for a lot. It does take some learning as you can get into a situation where the rudders and prop thrust are at odds.

A simple solution would be an electric motor mounted where the engine block is on the outboard. No need to redesign the boat...I believe there are a few sources doing this already...but you are back to the issue of how to feed it large amounts of electricity.

[tp12]

Originally Posted by valhalla360

Assuming the centrally mounted drive is steerable, you don't lose nearly as much as you might think. Yes, twins are still better but the ability to direct the thrust makes up for a lot. It does take some learning as you can get into a situation where the rudders and prop thrust are at odds.

A simple solution would be an electric motor mounted where the engine block is on the outboard. No need to redesign the boat...I believe there are a few sources doing this already...but you are back to the issue of how to feed it large amounts of electricity.

Jeff mentioned the bowthrusters so I'll assume it's not steerable. I'll dust off my google-** to see about mounting the electric motor on the outboard.

Cheers!

[BigBeakie]

Originally Posted by tp12

Jeff mentioned the bowthrusters so I'll assume it's not steerable. I'll dust off my google-** to see about mounting the electric motor on the outboard.

Cheers!

Consider the advantages of Jeff putting on 100mm beaching keels. Depending on where you want to go cruising and how remote you'll be, they come in handy for working on your underwater areas without hunting for a wide enough travel lift.

Under that nice sand bank lurks a rock or big chunk of coral rubble....

[valhalla360]

Originally Posted by tp12

Jeff mentioned the bowthrusters so I'll assume it's not steerable. I'll dust off my google-** to see about mounting the electric motor on the outboard.

Cheers!

Might be the case but I've yet to see a cat with a single central motor that wasn't steerable.
- One really cool design had a lever near the helm so you could turn the motor independent of the rudders.

That would be a pig around the docks (without bow thrusters) as you would need to be making way to have any steering beyond a bit of paddle wheel effect (and I'm not sure the paddle wheel effect would work well on a cat).

[catsketcher]

I had a non steerable single outboard on my cat for about 17 years. I had the pulleys to make it steer but after some test didn't bother. Another cat with a way to steer the outboard found that the propwash hit the inside of one hull reducing the effect to a large degree.

To get a steerable outboard working well you have to mount it aft, so you get more lever arm and so the prop wash can go under the hulls. But you have to mount the motor forward so that it works well in waves. I rarely visited marinas so we pushed ours forward and didn't steer.

A year ago I went to twins - nice in many ways. The best thing about it is now there is no central nacelle banging on the waves - I tried three different pifting nacelles and couldn't stand the banging. Now is nice and silent (from the motor). Still don't do marinas so the spinning ability is not needed much but I do like being able to keep the boat into the wind when pulling up the anchor slowly.

cheers

Phil

[tp12]

Originally Posted by valhalla360

Might be the case but I've yet to see a cat with a single central motor that wasn't steerable.
- One really cool design had a lever near the helm so you could turn the motor independent of the rudders.

That would be a pig around the docks (without bow thrusters) as you would need to be making way to have any steering beyond a bit of paddle wheel effect (and I'm not sure the paddle wheel effect would work well on a cat).

Yeah, it doesn't appeal to me. Worst case scenario though is that I would put two outboards in wells like they've done in the videos. Seems logical.

Originally Posted by catsketcher

I had a non steerable single outboard on my cat for about 17 years. I had the pulleys to make it steer but after some test didn't bother. Another cat with a way to steer the outboard found that the propwash hit the inside of one hull reducing the effect to a large degree.

To get a steerable outboard working well you have to mount it aft, so you get more lever arm and so the prop wash can go under the hulls. But you have to mount the motor forward so that it works well in waves. I rarely visited marinas so we pushed ours forward and didn't steer.

A year ago I went to twins - nice in many ways. The best thing about it is now there is no central nacelle banging on the waves - I tried three different pifting nacelles and couldn't stand the banging. Now is nice and silent (from the motor). Still don't do marinas so the spinning ability is not needed much but I do like being able to keep the boat into the wind when pulling up the anchor slowly.

cheers

Phil

The nacelle made that much noise? You've convinced me it's a bad idea. There's two many disadvantages for that approach for me.

Thanks Gents, appreciate your help.

[44'cruisingcat]

There's a few downsides to wells also.

You are forced into "walk over" cockpit access, and it can be quite a steep climb, as outboards are quite tall.

Engines can corrode quickly, due to the extremely humid environment.

Forced ventilation is essential when the motors are running or they can asphyxiate themselves.

Access to the gearcase fill and drain plugs is restricted, a friend with a Schionning has to slip his boat to change gear oil, he cant do it sitting on a beach.

The engine wells do hold water, which is added weight. And barnacles can grow there, and on the props and gearboxes, and they're not easy to scrape off. The same friend spent quite some time hanging upside down scraping barnies and vomiting down the well. Wasn't selling the idea to me, I can tell you!

[tp12]

Originally Posted by 44'cruisingcat

There's a few downsides to wells also.

You are forced into "walk over" cockpit access, and it can be quite a steep climb, as outboards are quite tall.

Engines can corrode quickly, due to the extremely humid environment.

Forced ventilation is essential when the motors are running or they can asphyxiate themselves.

Access to the gearcase fill and drain plugs is restricted, a friend with a Schionning has to slip his boat to change gear oil, he cant do it sitting on a beach.

The engine wells do hold water, which is added weight. And barnacles can grow there, and on the props and gearboxes, and they're not easy to scrape off. The same friend spent quite some time hanging upside down scraping barnies and vomiting down the well. Wasn't selling the idea to me, I can tell you!

Well, if you'd let me bring a 6 pack/bottle of whisky on board perhaps I could view Bob's drop down legs [emoji6] hahaha. Just jokes mate.

Thanks, Alan, I appreciate your comments. I find myself spread between several designs that all have great ideas. The cost effective option is to pick one and not mod it. The best option seems to be to pick a design as a base and work with the designer to add other ideas.

If I only I knew someone, with a solid build history, who was thinking of going to a bigger design, whom I could pay to build one of two boats and amortise costs ..... I'm racking my brain .... [emoji6]