7 M length 3.5 Breadth Round bottom without skeg & single OBM in the center line of vessel

Hi,

Recently I was working with a project , a 7 meter length catamaran boat with round bottom hull shape and 3. 5 meter depth.The boat is equipped with 6 kW OBM in centerline of boat with only one OBM.
Please note that we had no skeg in the hull. At present when we taken the boat for trials. The boat was making round and not able to go straight. Even the OBM kept straight, the boat is making circles.
Any idea about how to rectify. Can we add skeg to hull ? Do we have calculation to skeg area for directional stability.

 

how about some pics? your boat is 7 long and 3.5m deep? like a 1/2 circle???

 

I will second Squidly's request for some photos.
I think (at least I hope) he means that the beam is 3.5 m., not the depth!

How far forward of the transoms is the outboard motor mounted?
It does seem strange that she just wants to go around in circles.

 

Are the hulls accurately aligned ( parallel )?
Towed in or out a bit?

Photos please.

 

The center of lateral area is too far forward, and probably forward of center of gravity. Try to trim her down aft and see what happens.

 

Naturally if the drive is more at less at the centre of lateral resistance, the steering won't work, as to why it won't run straight even with motor pointing dead ahead, well that could be attributable to a number of things. Fitting rudders to the stern would be a fix.

 

Happy to inform that we have put additional skeg connected to transom of the vessel.This helped to acquire the directional stability for the catamaran vessel- Depth of the hull was 1.06 m..The hull shape was round bottom hull- displacement hull

 

The little motor is 6KW ?

 

Yes it is a 6 kW electric outboard

 

Looks like you have made good progress, does that run off your solar panels ?

 

Yes we have around 2 kW solar modules on roof which charges the battery bank of 15 kWH Lithium ion phosphate battery pack. Additional to this we have a genset which can charge the battery pack. Presently boat can travel at a speed of 4-5 knots at 4kw ( We have limited the power).

 

That is interesting, but I expect facing headwinds is not your preferred heading !

 

Skeg was provided & vessel got directional stability