MaxProp 17"

Probably an old chestnut but have owned 1976 38 since Oct06 and am unhappy with performance ofMaxprop+ Bukh 24 HP. Have reset to 22 deg and still smoke at 2400 revs + slow response with port propwalk in reverse.

Anyone got experience with 2 blade props from NZ , or 4 bladers

Thankyou

Alasdair

Dear Alasdair,
about the (black) smoke try to set the injection pump (must be done by a professional mechanic). May be you have too much diesel into the pump and it does not burn completely.
As I think I have already told you I am very happy with my new 16" 4 blades VariProp, German built propeller, you can set the pitch very sharply, under water and in a matter of minutes, but don't think to get a better speed, what is fantastic is you o really forget noise and vibration!
Fair winds!
Matteo

I am posting this reply to Alasdair on behalf of Lars Strom:

Alasdair
In order to analyze the situation and provide recommendations it is necessary to know the full throttle rpm and speed achieved, as well as the reduction ratio and number of blades. Bukh is peculiar as they provide three different ratings, each associated with a particular maximum rpm. What is you main interest - best top speed or good cruising speeds at low rpm? Usually a compromise is chosen, i.e. the 3000 rpm rating

17" means there is rather small clearance between propeller and hull, this increases propeller walk.
With a right handed prop you get port prop walk in reverse as reported.
Feathering props from different manufactureres perform about the same, folding props are more efficient due to twisted blades
Lars

Hi Matteo? Lars.

Thankyou both for your advice, steep learning curve !

Had her out last week and found prop set at 24 degrees, so reduced pitch- as you suggested Matteo - to 22. This was agreed by engineer after I gave him sea trial info. Achieved 3200 revs max at 6.8 knots with less smoking and propwalk so will leave it there until engine service during winter.

Spectacular sights this w/e off Cowes with Swan European regatta- intend to enter in'09.

Thankyou again

Alasdair

Dear Alasdair, I am posting this on behalf of Lars:

Alastair
Based on the information you give the pitch and speed are fairly right, but smoking should not occur.
Injection system to be checked.
Unless you ran speed trials in shallow water the top speed could also be a little higher, possibly this is now affected by injection system.
Does the prop have 2 or 3 blades?
Lars