Installing bow thruster 260 Sundancer

[Roland Illvesand]

The tunnel fits in the holes.

 

[Henry Boyd]

Roland,

Lookin good. Is the tube glassed to the hull and then trimmed, or trimmed and then glassed to the hull?

What is the aluminum frame under the boat? It looks too complicated to be a trailer.

 

[ErikE]

Wow....my palms started sweating just seeing the holes in the boat. I don't think I could have done it!!

Awesome project. Looking forward to seeing the rest.

 

[Roland Illvesand]

Roland,

Lookin good. Is the tube glassed to the hull and then trimmed, or trimmed and then glassed to the hull?

What is the aluminum frame under the boat? It looks too complicated to be a trailer.

It will be trimmed before glassed to the hull. The aluminium frame is just a support for the boat during land storage.

 

[Henry Boyd]

That is really interesting. Is it something you designed as a custom boat holder, or is it a commercial product in Sweden?

 

[Roland Illvesand]

That is really interesting. Is it something you designed as a custom boat holder, or is it a commercial product in Sweden?

It’s a commercial product and lot’s of us use it here.

https://www.press-son.se/butik/produkt-kategori/battillbehor/baten-pa-land/batbockar/

 

[Roland Illvesand]

Now are the tunnel casted to the hull, tomorow it will be another layer.
Then only putty, sanding and painting are left on the outside and on the inside painting and mount the electric motor.

 

[Henry Boyd]

Lookin good! Has the boating season started? You look like you are down to the wire.

 

[Roland Illvesand]

Lookin good! Has the boating season started? You look like you are down to the wire.

Splash time on friday

 

[Roland Illvesand]

First filling done!

 

[douglee25]

I remember reading something at one point, what is the reasoning that the back side of the tube isn't flush with the hull? Does that help prevent cavitation?

Looks good!

 

[Roland Illvesand]

I remember reading something at one point, what is the reasoning that the back side of the tube isn't flush with the hull? Does that help prevent cavitation?

Looks good!

This is from the istallation manual.

High-Speed Boats
Tunnel lengths must be increased to protect the propeller from damage when crashing against the water surface during high-speed cruising.

1. A possible problem in sail boats or fast powerboats is that a non-rounded surface can generate drag from the back face of the tunnel, as it creates a“fl at” area facing the fl ow of water (1).

This problem can be solved in two different ways, depending on what is possible or easier to perform.

2. The best solution which generally reduces the most drag is to make a recess in the hull at the back of the tunnel. As the back face is removed water can flow freely past the tunnel entry. The depth and shape of this recess will depend on the boat and the angle facing up/ down aft of the tunnel insert. Normally it is angled slightly down because of the water flow on this area (2).

3. Making a deflector/ spoiler in front and underneath the tunnel can also reduce damage to the thruster and drag. The deflector/ spoiler will push the
water flow out from the hull so water can pass by the back face of the tunnel. The shape and size of this deflector/ spoiler will depend on the hull shape.
The easiest way of making the deflector/ spoiler is to retain a part of the lower forward area of the tunnel while installing the tube. Use this area as support to mould a soft curve/spoiler shape from the hull. (3).

 

[JimG]

The way I read that makes yours look backwards... sorry, probably just me.

 

[Blueone]

Bump at the front...flat at the back...looks okay to me.

 

[copb8tx]

The way I read that makes yours look backwards... sorry, probably just me.

Me too. Having the lip on the front certainly makes sense for diverting the water away from the opening when pushing water. I can't see how have the lip on the trailing edge helps at all. If anything it'll have a tendency to 'scoop' water towards the blades.

 

[JimG]

Yep, I knew it was just me... I was having trouble determining which direction the bow was. I see that now.

 

[douglee25]

This is from the istallation manual.

High-Speed Boats
Tunnel lengths must be increased to protect the propeller from damage when crashing against the water surface during high-speed cruising.

1. A possible problem in sail boats or fast powerboats is that a non-rounded surface can generate drag from the back face of the tunnel, as it creates a“fl at” area facing the fl ow of water (1).

This problem can be solved in two different ways, depending on what is possible or easier to perform.

2. The best solution which generally reduces the most drag is to make a recess in the hull at the back of the tunnel. As the back face is removed water can flow freely past the tunnel entry. The depth and shape of this recess will depend on the boat and the angle facing up/ down aft of the tunnel insert. Normally it is angled slightly down because of the water flow on this area (2).

3. Making a deflector/ spoiler in front and underneath the tunnel can also reduce damage to the thruster and drag. The deflector/ spoiler will push the
water flow out from the hull so water can pass by the back face of the tunnel. The shape and size of this deflector/ spoiler will depend on the hull shape.
The easiest way of making the deflector/ spoiler is to retain a part of the lower forward area of the tunnel while installing the tube. Use this area as support to mould a soft curve/spoiler shape from the hull. (3).

Thanks for the info.

 

[copb8tx]

At first I was looking at your boat backwards. Once I uncrossed my eyes it appears you've done a perfect job.

Even if it were backwards I'd still be totally impressed.

 

[Roland Illvesand]

The propeller and the electric motor are test mounted before I will paint everything.

 

[tc410]

Assuming your boat floats when you launch her, I’d like to nominate this for the 2021 “CSR Best Do-It-Yourself” award.

I have to say, it takes a lot of nerve and confidence to drill that big of a hole in something that is supposed to float!