Repower Glander Tavana (MD2B replacement

yawlsailor · Member

Repower Glander Tavana (MD2B replacement

Stanley · Guru

Hi,

The good news for you is that your engine compartment is about to get much larger. All of the engines that you are looking at are much smaller than the old Volvo so whichever you choose will have much more room around it than you are used to.

I dont know your boat so without more information, it is difficult to give you a definate recommendation. Right now I would think that the Beta 20 (BD722) with 2.6:1 transmission will be fine. Expect to get a new propeller as the new engine will want a right hand propeller instead of the LH that the Volvo used.

If you can let me know the hull form of your boat and the waterline length, I can work out propeller calculations for you.

Stanley

yawlsailor · Member

The Tavana is a traditional full keel with centerboard. 10 foot beem. 3 foot draft with the centerboard up. This is significant as the shallow draft leads to a small aperture for the prop. A 13 inch three blade prop is the standard configuration. The prop is also somewhat shadowed by the keel so motoring performance has never been great. The existing volvo is mounted at a slant to match the prop shaft. I will have to measure it but the 7 or 8 degrees listed in your alternate transmissions looks about right.

yawlsailor · Member

I left off the one dimension you asked for: LWL is 26 ft

Stanley · Guru

If you use the Beta 20 with 2:1 transmission the prop calc comes up with 6.5Knot boat speed using a 13"x9" three blade RH propeller with 50% BAR (blade area ratio).

If you use the Beta 25 with 2:1 transmission the prop calc comes up with 6.5Knot boat speed using 13"x10" three blade RH propeller with 50% BAR.

When you say that your engine is in at an angle, please clarify. Is the shaft at a different angle and down 7 degree angle from the engine or is the shaft at exactly the same angle as the engine?

yawlsailor · Member

The prop shaft is in line with the crankshaft. The engine bed and stern tube have the angle built into them. I am not sure what the angle is. I will measure it this weekend. What angle is acceptable for mounting the engine? It looks like the transmission with the angled output shaft adds about $1K to the cost of the system

Stanley · Guru

If your engine and shaft are directly in line, you need the standard TMC40 transmission. You can see the drawing at this link http://www.betamarinenc.com/bd722.htm (click on the detailed pdf drawing). You need to copy and paste the link. I don't know why these posted links dont work on this forum.

The engine will accept up to 15 degree angle off level as a constant but will be much better off at 5 to 8 degrees. This allows for plenty of safety margin as the boat rolls while motoring and makes for an easier installation. I have seen these old Volvo's on different mount centers and we can provide the Beta 20 and Beta 25 on 14.5" or 16" centers (port to stbd) so there should be no problem with your engine beds.

-- Edited by Stanley on Friday 2nd of July 2010 08:41:08 AM

yawlsailor · Member

Stanley, Thanks for all the help. I will measure everything this weekend and decide which way I want to go. Is there any advantage to going to the BD1005 or would it just be wasted horsepower?
In your prop calculations, at what RPM would the boat achieve hull speed?

Stanley · Guru

The BD1005 will only cost you more money and wont improve the boat performance. The only instance that I would advise you to go up to this engine is if you wanted to use a 100 amp alternator and a refrigeration compressor. As this engine is a larger engine than the 20 and 25, it is much easier to fit and drive these larger accessories.

Generally, you can expect close to hull speed at approx 75% of engine speed. This will leave a lot in reserve for those occasions when it is needed.
Stanley

yawlsailor · Member

We got the old Volvo out this weekend and I had a chance to look at the engine beds. No detailed measurements yet but they appear to be at more than a 15 degree angle so I will likely need one of the transmissions with the angled output shaft.
The other issue is the relative position of the centerline of the prop shaft to the plane of the engine bed. The prop shaft is approximately 3/4 inch below the bed. If I go with the straight in-line engine and shaft, the engine brackets would have to be modified to drop the engine. Is this easy to do? They had the volvo droped as low as it could go on the isolators (eliminated the lower nut) and shimed under the isolators instead of using the bolts.
If I go with the angled output shaft this can be worked out with the new engine beds. With a straight in-line shaft I would need the modified engine brackets or would have to move the engine forward enough to be able to modify the bed to shaft dimension.

Stanley · Guru

Here is the link to the drawing of the Beta 20 with the 7 degree down angle transmission http://www.betamarinenc.com/images/Beta%2020%20HE%20TTMC35A%20100-06359.pdf

The Beta 25 version is here http://www.betamarinenc.com/images/Beta%2025%20HE%20TTMC35A%20100-06494.pdf

Regards, Stanley

yawlsailor · Member

Hi Stanley,
Thanks for the links to the engines with the down angle gear boxes. I made lots of measurements this weekend. It looks like I will go with the Beta 20 with the 7 degree down angle. Which gear ratio would you recommend (and what prop to match)? The old Volvo mounted on 16 inch centers on the isolators. Do you have a standard bracket set to match?

Stanley · Guru

I would use the Beta 20 with the 2.33:1 down angle transmission.
The propeller called for is 13"x11" three blade RH with 50% BAR.
We can supply the engine on 16" centers. This is actually quite common as many of the old small Volvo's had this mount size. We call these mounts Albin Vega mounts because they were originally designed for the Albin Vega.