aquasport 246cc diesel tunnel drive

[Capt. Bob]

Since we're all chiming in on his project, everyone please take note......

Eric posted a link to his photos. If you go there, you will see he is using a Hurth HSW 630 V Drive. Meaningless to me but just curious so I "Googled" it and it appears to have a gear ratio of 1.56. I'm not sure if that's correct.

Also, Eric appears to be leaning toward a 18 x 24 4 bladed prop (as per the photo, though he posted a 18 x 26, typo maybe?).

Eric needs to chime in here to confirm or deny my thoughts.

This is turning into a great learning experience.

Thanks.

[saltfly]

This going to be a very interesting thread to follow. I agree with captbob. I’m really looking forward to follow this to completion. You never know, this may start a whole  new trend.

[GoneFission]

I spent a good deal on time on one of those Penn-Yans back in the 70s...  Nice boats.  

Here's a nice thread on a 25 Bertram that got a tunnel/pocket:
http://www.cssims.com/25_bertram_prop_pocket.htm  

Here's a Carolina boat being overhauled with a pocket:
http://www.fishbiteme.com/images/DSC00059res.jpg  

And why do the prop pocket?  Take a guess what the power is:
http://www.boatdesign.net/forums/attach ... et-007.jpg

[Capt. Bob]

The Bertram is a good read. Noticed about the dry stuffing box caused by the pocket. Kinda gets one thinking about Dave's Evolution Marine shaft link.
I would guess that Eric, having done several conversions has that worked though this by now.

I was waiting for you to chime in CJ.
Good stuff.

[dburr]

Mod Edit by permission for thread continuity and to increase understanding of this subject by all members.

(Edit: CB if this post doesn't make sense anymore delete it as appropriate, context maybe lost, it seems like I am making a random turret’s type statement maybe? Any/all mention of blade load is gone I think.. Don't need people here calling me Crazy Dave too..)

Care must be exercised with all assumptions.....  

With tweaking, Eric is expecting 220hp +/- at roughly 2600 rpm with the gear at 1.56 that gives 1666 at the wheel with a tip speed of about 77kts.  It will be near the edge of performance for an 18 inch wheel at that speed.

With a four or 5 bladed wheel, I am having trouble seeing where blade load will be problem.

If I am incorrect in my thinking by all means let me know, we are all here to learn and assist when we can..

[Capt. Bob]

Eric, aka go2sea, please update when you get a chance.

This is a very interesting rebuild.

Thanks!

[Capt. Bob]

I don't don't know if Eric will be returning but if you want to see some interesting stuff and gain a little insight on this member, go back to his first post and click on his photo link. Then browse all his photos. This Aqua, as he stated his first, is just one of a number of things this gentleman has undertaken and experienced. Quite interesting really and a missed opportunity for the Forum.

[gon2sea]

im still here...lol.., the last few days i have been working outside ( working 4 -10 hr days ) and in arizona it can be brutal especially during monsoon season with higher humidity, so, evey now and then i simply come home beat... darn, wish i was 20 again.. well, not really just wish i had the energy.
many of our projects, at least many of mine are somewhat influenced by fund limitations, i would love to go with a 4 blade 18 x 24" prop but since i found a used 3 blade 18x26 in like new condition for $125 that is what i will go with as a starting point, got the motor mount brackets made this morning and am in the process of lifting the engine into the boat, had to take some time out to run into phoenix to get 5 gallons of laminating resin and 10 yards of 1708 biaxial glass for the tunnel, so i hope to have my shaft angle figured out by tomorrow so i can start working on the tunnel, the vdrive is  12 degrees, a bit more than i would like so i think then engine will have to be angled to flatten the shaft.
i really appreciate all the feed back and thoughts and links, lots of interesting articles and knowledgeable bunch...
Eric

[gon2sea]

added a few pictures to the link...
https://picasaweb.google.com/1049052607 ... 3405177458

i tried uploading a picture but i think my file size was too big...
Eric

[dburr]

When you get a chance Eric take a look at the top of the page and find View Messages right next to log out.... You have a few PM's waiting!  

Stay out of the hot sun!!!  

[Capt. Bob]

OK I'll bite,

What's wrong with this photo? The hull, engine or me?

[seabob4]

Nary a thing CB, except 1 too many mufflers...unless he plans to split the exhaust.  The Cummins is a I6, so only 1 exhaust manifold...

You're not talking about the engine being bassackwards, are you?  Remember, V-drive bud, V-drive...

[dburr]

Beat me to it SB!  
 

Unless I am mistaken, we are soon gonna see the V-drive hard mounted to the hull forward of the engine a little ways.  The thrust from the wheel is transmitted to the hull through the V-drive itself.  The V-drive can be connected to the engine with something like a Spicer drive shaft (U joint on either end) allowing for the engine and gear to be truly soft mounted reducing engine noise and vibration transmitted to the hull making things quiet..  

This is cool aint it? 8)

To keep the noise down Eric where are you going to exit the exhaust?

[Capt. Bob]

I'll be damned.

Like this eh.


So the gears inside the the V drive itself are shaped for the angle of the "V"?
I'll assume there is a standard degree or can you fiddle with the angle?

[seabob4]

CB,
On some cruisers, Sea Ray for instance on the Sun Dancers, the motor will be aft, connected to a tranny via a short drive shaft where the tranny lives under the settee in the aft cabin.  Then of course, the prop shaft heads back the other way out the hull bottom...

Like I said earlier, v-drives optimize cabin room. Or cockpit room.  So Eric's idea is good, considering he has the parts. If the motor is to be located mid-ships, either under the console or the leaning post, then straight shot is the way to go...