Rolly custom steel motorboat

I am not familiar with the prices today, so I need to ask; what would it cost me, if I hire an NA to create the drawing for this project?

 

It really depends upon their experience and knowledge and of course how much scope you wish them to do.
It is generally 'better' if you can source a NA that is local to you too...

Once you find a NA, explain the scope of work and you'll get a quote from them, only then can you decide if the price is worth it, or to reduce/increase your scope of work.

 

It should not be tooo difficult to retrofit a mast and a couple of outriggers so that you can use stabilising paravanes while underway.

The Nordhavn 46 in the photo below is showing them off very nicely here - and they do have a huge effect in reducing her rolling.
Starlet has been across the Pacific, and across the Atlantic a couple of times, and she always had her paravanes rigged when on a passage (unless perhaps the sea was flat calm).


Some good info about paravanes in this post on Mobius' Blog -
Archives | Möbius World https://mobius.world/2022/06/

I found the Mobius link by typing 'photos trawler yachts with paravanes' in to Google Search, and many other interesting links came up as well.

Edit - a question about your 220 hp Cat propulsion engine.
This much power 'should' be more than enough to push your vessel to hull speed quite happily, yet you comment that she is a bit slow, with a cruising speed of 6 knots.
What are the engine revs for 6 knots?
What is the reduction ratio on the gearbox? Are you able to achieve the full revs of the engine with this gearbox? And what is the maximum speed at full engine revs?
The photos suggest that you might be able to increase the diameter of the propeller - what is the current clearance between the blades and the underside of the hull, and between the blades and the skeg below?

 

A boat or two ago had poles with a hinge and pin system that was pretty sweet. Kept the poles locked down, id put them out like arms when walking a beam. Paravanes slowed it down a half a knot, so we just let it roll. Let me look and see if I still have pics on an old phone. Paravanses are a pretty easy welding project, although kolstrand sells them off the shelf.

 

I don't think I could handle the paravanes in rough weather. My age and being single handed just makes it too risky. Plus, my boat does not have walk around, so deploying the paravanes could be very challenging.

At 1500 rpm the boat is cruising 6-6.5 knots. At 1600 rpm maybe close to 7 knots. At 1800 rpm will go almost 8 knots, but not steady and the consumption goes up significantly.
I do not know the ratio of the gearbox. I need to find some documentation on this.
Here are photos of the prop.

 

Yesterday, I have visited two local boatyards to get info about bilge keels installation. They both had metal fabrication shops. One was focused on pleasure boats and race boats. The other is mainly commercial and fishing boats focused. The employee at both front desks gave me the impression right at the beginning that have never dealt with an order like this. They offered to take a look, - requires haul out for around $900 - and go from there, but no familiarity was shown about bilge keels. I showed them pictures about what I was looking for, which helped. I decided not to pursue this angle, since I don't want my boat to be a testing ground.
Is there a database or organization of NA pros, where I could search for one?

 

These were the photos I showed to the front desk.
I like picture #3 the most. Although, the hull is not as deep as mine. The swim platform can be helpful with the following seas.

 

I don't know of the yards around astoria, but I'd be shocked of you couldn't scare someone up who hasn't done rolling chocks on a steel boat. Nowadays all the fishing boats have them, but 15 to 20 years ago everyone was being retrofit. Would think someone around yaquina could figure it out.

Guys around here don't usually employ a naval architect for them, probably should but enough have been done it's a lot of monkey see monkey do. Most are a version of picture number two.

 

That sounds very surprising to me.

Agreed on both counts!

In the US one is required to be licenced for being a NA, so there is a database, either Google search or a SNAME membership search.
Or contact your local Coastguard Office.

If you have no luck, you can either post more details of your vessel here, for the "masses" to comment upon.
or
You can send me an email, and we can do this together.

 

Or you can do both...... and you can take on board what the masses say, but if I was you I would definitely go with what Ad H0c suggests, re doing it together.

 

At the yard where I did the haul out, there is a welder who does most of the steel work on the boats. Mostly fishing boats. Yes, he has done several rolling chokes, but not bilge keels. He would weld it on, but he told me that designing it I would need an architect. He has not done one before. Only chokes.
I will continue to search for a NA, but I'd prefer someone who is in the area. I plan to haul out again next summer for other reasons and having someone close by could simplify to get the proper measurements of the hull. As I said, I do not have any documentation I could give to a NA. I don't even know what data a NA would require?

 

I certainly appreciate any help, either way. I am learning about my boat already.
What would the members here require me to post? What data?

 

This is picture of my boat, when it was launched in 2000. I suspect, those alterations have not happened yet, at that time. The upper structure looks much lower, but it could be just an imagination.

 

I can't see your email on your profile, but I initiated a conversation with you. Thanks.

 

SNAME does not allow search without membership.