Hull modifications

Update

Guys, here is an update on my project.

Absolutely no physical progress to report. The Yard foreman talked me into a speaking with a naval architect before proceeding. His report came today.

The report pretty much confirms my ideas, but has a bit more meat behind the "why?" part.

 

Looks about right. I am certain you did the right thing having it designed properly.

You may nudge the 20kts yet.

I wonder what weight they used for the drag determination. Did you manage to get an actual weight?

You will get gains from bigger engines, bigger props and reduced appendages. Will still take a lot of fuel to push over 14kts. May not have the heavy weather/ heavy load capacity of the current props. Geared more toward speed than workboat.

No doubt you will have at least one interested, if remote, observer in the outcome from the re-commissioning.

Now just a matter of keeping an eye on the workmanship. Prop strut and rudder mounts will be heavily loaded points.

Rick W.

 

Rick,

I never did get a good weight. The naval architect used 7.5LT. I am guessing he took some measurements and made a crude estimate of the block coefficient and determined the displacement. I actually asked the same question today. I'll let you know his response.

I'm not too worried about losing the load capacity of the current props. The boat will never again carry the loads it was intended to, as she is now a light commercial and sport fishing charter vessel. Speed and economy are my current priorities.

A lot of people think i am crazy for making this modification. I do believe the increase of 6 knots is worth the trouble. Hopefully the boat will be more efficient and justifying the cost of the improvements. Fuel savings may not be realized for many years.

Now the big question...who specializes in refinancing poor boat owners through ridiculous yard periods??

 

Would have been good to get a starting weight. Even a good photo of where she sat in the water before any mods. Getting weight out is one certain way to save fuel.

I am trying to fund my own little projects while building my retirements funds but just treading water with the sharemarket is doing its best to make me poor. So I am not in a position to help.

Best of luck with the funding. I do hope you get up around the 20kts. Keep us posted on progress.

Rick

 

Hey MKP,
Good to see you and your project back. Sounds like you're going ahead full steam. It's a shame the travel lift at the yard you're laid up in doesn't have a strain gauge to get a weight. I'm trying to sweet talk the local guys to make a quick 1 minute pick and drop to get an accurate weight for my boat and my records.

The yard I do my regular haulouts at has to use a carriage and a ways before they can pick with a travel lift. Much more hassle and time involved. I am quite annoyed with myself for not getting a weight reading last time I hauled. All I had to do was ask!

Keep us posted, I am quite interested in your project.

 

21Aug08 Update

Finally got a solid week of work in from the yard. Things are going slow, but at least moving in the right direction. Rudders and steering gear ordered today. I found a guy at Yacht Supply Depot that has great prices if anyone needs Buck Algonquin parts.

5 days rough days and the shaft keels are completely gone. Only a small piece is left to hold the cutlass bearing.

I think I am going to spend the extra money for Aquamet 22 Shafts instead of AQ 19.

Do you guys have a shaft material preference?

Next week the glass work begins and hopefully some rudder hanging.

Pictures from the week:

 

Hey Guys. I finally got the boat back in the water!

Here is the official report (performance specs to follow):

On June 12th I hauled her out for a bottom job and a quick evaluation by a Naval Architect. Well...one thing turned into another and now, four months later, she is back.

I have been toying with ideas to make her faster and more efficient. She originally had triple keels. One center-line and one for each shaft. The shaft keels had huge steel shoes and cages around the running gear. This was for working in the shallow waters of Bristol bay and jumping gillnets. -none of which is required locally. All this extra gear was added weight and drag.









In addition to a bottom job and a hull polish, I planned to reduce as much as possible drag on the boats bottom, relocate the wheels and rudders to make her a little more streamlined. The naval architect's report confirmed my theory. So one afternoon I armed myself with a case Coors, two dozen sawzall blades, and a Tyvek suit and got busy.









Basically everything that wasn't hydrodynamic or absolutely necessary was removed.



The new free hanging spade rudders were moved aft for a greater steering moment. The new foil rudders replaced old flat plate skeg rudders and should be 30% more efficient.



Shafts were enlarged and extended to move the wheels aft by 2' to throw a larger wheel. With the removal of shaft keels, nothing was in place to hold a bearing, so two struts were fabricated and a second cutlass bearing was placed at the new shaft log location.









Numerous other related projects were accomplished during this time. You know how it goes: "well while we've already got that open, so we might as well..."

In hine sight the project was far more expensive and longer than I ever expected. This was not a financially smart endeavor. I do not know the exact fuel savings yet, but I can predict it will take many many years to offset the cost of this modification. I'm more of an Ops guy than a bean counter!

Finishing touches:


New Interceptor Trim Tabs:


Back in the water:




More pictures here:http://s47.photobucket.com/albums/f193/mkp77/Blizzard 08 Retrofit/

 

That looks like 4 months of satisfaction. Looks much "cleaner" underwater now. I said at the beginning it was a brave move and would be hard to justify economically but it does look nice now. I believe you got some good input on the detail design it looks robust.

So did you get to 20 knots?

Did you get a weight when relaunching?

What size are the props? They look nice by the way. They are monsters compared with most.

Any estimate of fuel saving yet?

Is she more responsive now? Not skittish down a wave?

Rick W.

 

Seatrails are planned for tomorrow. Still finishing up some steering issues.

Weight on the travel lift was 15k lbs close, but seems a little lite to me.

I moved up from 24 x 18 to 24 x 21. Sounded like a good place to start. The boat has room for 28".

I will report tomorrow night on the performance specs.

Thanks for all your input!

Mike

 

Congratulations!

You've accomplished a great deal. I am extremely interested in the results of your trials. Now the hard part...dialing it in. Once again, congratulations!

TollyWally

 

I'm worried the rudders aren't big enough.

Here are some interior pictures of the new rudder Assembly. I turned the tillers facing aft for more work/storage room:

 

Finally got some time to write up the seatrial data. -See attached

At WOT I saw 19.2 knots with a marginal load. Engines are rated for 2600 rpm at full load, but I am still seeing 2840. Governor is set at 3030.
I may still pitch up a few inches.

Tachs are off a bit, but equally between the two engines.

 

Great data to have for future reference. I will have to see how it compares with estimates.

Almost where you wanted to be. Will be interesting if a bigger pitch will make it to 20kts.

One other thing I thought about from your photos. The one showing the rudder shaft support. It does not seem that there is good transverse restraint of the upper bearing. The prop is producing a side load so the bearing needs good transverse restraint. It may have it but there is no transverse web visible in the photo.

Rick W.

 

From 14.7 to 19.2 kts is a big gain. I wonder if you will save fuel?

Looks like your previous top speed will now be the economic cruise speed. From the charts that should be 1nmpg at 14kts. I cannot recall if you posted a figure previously.

Rick W

 

Mark
I just went back through the posts. Hope you did not need to kill anyone!!!

Seems like it is close to where you wanted to be.

The one other thing that you were after was better handling downhill. Do the new rudders achieve this?

Rick W