Propeller Size mistake!

[Rick Bettua]

Hello All

The great thing about forum as such is you get to share information about what you love with other folks so hopefully they don't go down the same road as you!

I posted some great numbers on my intial sea trial with a new Edencraft 233 and a Single Yamaha 350 V-8.   The numbers we based on a full tank of fuel (555 liters), 2 adults, 3 AGM batteries, winch and with the top installed.  48kts @ 5500 rpm sucking down 95 liters per hour! Turning a 16.5" X 19" Four Blade PowerTech.

Now that was my intial idea of testing a boat under loaded conditions.  I figured this was good because on Yamaha Performance reports that is typically how each of the test boats are loaded. MY MISTAKE !

My new definition is simply: "what you are carrying at the end of a fishing day".  We freedive to spearfish so what was in the boat at the end of the day?  4 Divers with  wet gear and a cooler of fish and ice weighing another 175 kgs.

New numbers are 42 kts @ 4950 rpm, loaded !  I spoke to PowerTech and they recommend dropping down to a 16.5" X 17" Four Blade.  Lucky for me they have a great program and will swap the prop for me.  

The new prop will sure shave that TOP End speed down a bit but what is more important to me is that 28-36kts speed.  I sure hope this helps someone out there or in the near future 

Cheers Rick

[Rick Bettua]

Hi David

I love the way the boat runs and feels but numbers don't lie. I knew when I saw the rpm guage I was not doing my new engine any favors by running that prop with a moderate to heavy load.

Other items on my list to tweek is to ad a "Power Assist Pump" to my steering system. I can point that V-8 in the right direction but to change course fast I need to use 2 hands.

I noticed that you ended up adding some weight up forward (batteries I think) I was thinking about adding my fresh water tank up forward. When that cooler is full at the end of the day it is of course all the way on the back deck so a little weight forward would be a welcome sight.

I can't wait to see your article, you deserve it for sure with the amount of time and energy you put into yours. I too have a front cover coming out, Spearfishing Down Under mag should be out by the middle of the month. Not my formula but shooting big doggies in Yap!

Cheers Dave

Rick

[Rick Bettua]

Hi David

Yes I saw they were expensive but I found a brand new one on ebay for just $600.  I already have the Garmin GHP-10 autopilot hooked into a Garmin 6212.  

Yes we took a few pics the other day while in the water, I will get one up soon.

[Rick Bettua]

Hi All

Ok we narrowed down the propeller size and the new numbers are as follows.  The folks at PowerTech Propellers made me a new prop 16.5 X 17" Four Blade, for our Yamaha 350 V-8.

The numbers at the end of the day were 45.6 kts @ 5800 rpm's (85Kph).  I had about 1/2 tank of fuel (275 ltr) 4 divers and the esky full.

On another note is this time out the Dana Trim Tabs were hooked up which were real nice addition especially at the slower speeds to bring the nose down but at WOT they were completely up.

I still want a little weight up forward so we are going to install a fresh water tank 95 ltrs under the forward hatch in the cabin.

Rick