TW28 Luka

To help other builders, please list the boat you are building in the Thread Subject -- and to conserve space, please limit your posting to one thread per boat.

Please feel free to use the gallery to display multiple images of your progress.
TW28RJ
Frequent Poster
Frequent Poster
Posts: 169
Joined: Tue Aug 21, 2007 2:44 pm
Location: Boston, Massachusetts

Re: TW28 Luka

Post by TW28RJ » Thu Dec 10, 2009 2:05 pm

Rick any considerations to install an angle drive transmission? That's what I've been thinking about lately. I believe that Cumhur used and angle drive.

Jacques, want to chime in here?



User avatar
Knottybuoyz
Very Active Poster
Very Active Poster
Posts: 2372
Joined: Sun Sep 03, 2006 8:09 pm
Location: Iroquois, ON Canada

Re: TW28 Luka

Post by Knottybuoyz » Thu Dec 10, 2009 2:18 pm

TW28RJ wrote:Rick any considerations to install an angle drive transmission? That's what I've been thinking about lately. I believe that Cumhur used and angle drive.
Jacques, want to chime in here?
None that I'm aware of. The down angle on the shaft is 8 degs. With the CV joint integral you can (and should have at least a 1-2 deg offset) up to 8 degs (which is he max the unit can handle). You can even have total misalignment, up and down and side to side if the total angles are no more than 8 degs. So you could mount the engine a few degs high or low and leave the down angle up to the CV joint. I'll probably let the CV joint take up 4-5 degs max.
Yours Aye! Rick
"It's not the boat "you built" until you've sworn at it, bled on it, sweated over it, cried beside it and then threatened to haul the POS outside and burn it!"

TW28RJ
Frequent Poster
Frequent Poster
Posts: 169
Joined: Tue Aug 21, 2007 2:44 pm
Location: Boston, Massachusetts

Re: TW28 Luka

Post by TW28RJ » Thu Dec 10, 2009 2:26 pm

That's interesting.. so if I went with a 7 degree down angle transmission I would be in good shape.

Bluefish2
* Bateau Builder *
* Bateau Builder *
Posts: 621
Joined: Thu Dec 27, 2007 8:20 pm
Location: North Shore Massachusetts

Re: TW28 Luka

Post by Bluefish2 » Thu Dec 10, 2009 7:43 pm

TW28RJ
Very impressive work. You are going to have quite a vessel when done. How many "partners" do you have at this point?
I am up to three now and only working on an FS171
great build,
BF2

TW28RJ
Frequent Poster
Frequent Poster
Posts: 169
Joined: Tue Aug 21, 2007 2:44 pm
Location: Boston, Massachusetts

Re: TW28 Luka

Post by TW28RJ » Fri Dec 11, 2009 8:14 pm

hey bluefish, this isn't my boat, it belongs to Peter, aka the broomside -

User avatar
TheBroomside
Active Poster
Active Poster
Posts: 368
Joined: Thu Jul 06, 2006 5:24 am
Location: Belgium

Re: TW28 Luka

Post by TheBroomside » Sat Dec 12, 2009 12:17 pm

TW28RJ wrote:Rick any considerations to install an angle drive transmission?
I do not know about the possible mechanical arguments pro or con a transmissioin with a downangle, but if you use a homokinetic coupling (Python, Aquadrive, ...) I see no particilar advantage.
As Rick pointed out, you need at least a 2° angle (max 8°) for the homokinetic coupling to function properly; this is related to the lubrication of the bearings. The angle of the shaft in our TW28 is 7.5°. So if you substract 3.5° for the homokinetic coupling, the remaining angle is 4°. Using a transmission with a downangle of 8° would mean that the engine needs to have a forward tilt of -4° . It will not hurt, but I do not see the point. Of course it would be a different thing if you would use a direct coupling.

Peter
LUS

TW28RJ
Frequent Poster
Frequent Poster
Posts: 169
Joined: Tue Aug 21, 2007 2:44 pm
Location: Boston, Massachusetts

Re: TW28 Luka

Post by TW28RJ » Sat Dec 12, 2009 6:13 pm

When I was thinking about the down angle transmission I wasn't thinking about an aquadrive or python drive, maybe a centiflex coupling or similar to allow the engine to float a bit. My main purpose was to install the engine level not at an incline - the benefit, slightly lower center of gravity and better lubricated engine. Thoughts?

User avatar
icelikkilinc
* Bateau Builder - Expert *
* Bateau Builder - Expert *
Posts: 708
Joined: Fri Sep 19, 2008 3:30 pm
Location: London / UK
Location: London / UK

Re: TW28 Luka

Post by icelikkilinc » Sun Dec 13, 2009 6:09 am

TW28RJ wrote:the benefit, slightly lower center of gravity and better lubricated engine. Thoughts?
No problem at all on lubrication.. 8 degrees on nearly 7 - 8 feet of shaft length is only a couple of cms on the engine.. Modern engines have oil pumps that will do the lubrication quite easily even on the angle mentioned.

Yes Cumhur ordered is VW 60 Hp engine with a ZF 8 degree down angle tranmission but I dont think you need to spend that extra money.. It is not that hard to find the alignment.

Image

Create a template for the engine and tranmission like above..

Image

.. I bought a 3 meter long steel pipe, 16 mm wide.. You can see the long pipe in the middle going to the coupling. That was a lead pipe for me to make the alignment. I still keep that template.
I calculated where the hole should be and just drilled a hole 17 mm wide. The hole was with 7 degree angle.. I made a wooden support before hand to attach to the back of keel so that I do not loose control of the drill and mess it up on the angle.
Than I placed the metal pipe through the keel to make sure it centers the coupling of the tranmission.
When the center was found, than I drilled the real sized hole. I used a 60 mm hole drill.What I did here, not to loose the angle is I used the same 3 meter pipe there.. I welded the drill to the 60 mm drill. Since the pipe is centered on the angle that I wanted, I just drilled it and it was really easy after that point.
Ilker

TW28 launch: viewtopic.php?f=12&t=23369

User avatar
TheBroomside
Active Poster
Active Poster
Posts: 368
Joined: Thu Jul 06, 2006 5:24 am
Location: Belgium

Re: TW28 Luka

Post by TheBroomside » Sun Dec 13, 2009 8:21 am

TW28RJ wrote:centiflex coupling or similar to allow the engine to float a bit.
I contacted Macca about this some time ago. He used a Bullflex coupling and was quite happy about this, also with regard to noise and vibrations. I guess a transmission with a downangle would make sense in that case, but as Ilkers points out, is absolutely not necessary.
Personally I still prefer all forces to be transmitted to the stringers and not the gearbox/engine, so I am quite happy with the Python drive.
Ilkers is right, installing and aligning the shaft/shaft tube was no big deal. By the way, Python drives sells an SS template which is extremely useful when installing the coupling.

Peter
LUS

ps. it would be nice to have an update on the TW28s of Macca and Cumhur.

User avatar
TheBroomside
Active Poster
Active Poster
Posts: 368
Joined: Thu Jul 06, 2006 5:24 am
Location: Belgium

Re: TW28 Luka

Post by TheBroomside » Sun Dec 13, 2009 8:39 am

Bluefish2 wrote:How many "partners" do you have at this point?
We are two building the TW28. We spent app 1600 hrs at the wharf (will not call this working hours, see some previous comments). We have some friends helping out for big tasks, they spent some 130 hrs at the workshop together.

Peter,
LUS

Post Reply

Who is online

Users browsing this forum: No registered users and 4 guests