martec prop

[ken matejka]

Hi, Does anyone know the proper size of martec elliptec prop for the H28.5?? I have seen diameter recommendations for both 14 and 16 as well as pitch recs for 10, 12, and 14. I think I am going to buy a used one but need to know the proper size. What sized do you have on your boats. Also, did it make a noticable difference in boat speed.thanks,Ken Matejka

 

[Terry]

Hi Ken, we had an H28 with a stock two

blade prop, which was perfect for the boat. She would cruise at around 6.2 knots (about hull speed) with engine turning at about 3000 RPM all day long. If we pushed the RPM to 3600 the boat would max at about 7 knots, well above the hull speed. I'm assuming your 28.5 performs about the same with the stock prop. I know nothing about the Martec prop. The two blade on our H28 worked so well I left it alone. A folding prop might make a small difference in speed under sail with reduced blade drag. It might be worth the conversion to some especially if they race.Terry

 

[Terrance M. Maloney]

H28 = 15X12

I had a Martec 15x12 that I took off of my H28 earlier this year and replaced with a fixed two blade because it caused the boat to not handle well under power. Granted it probably did provide some advantage under sail, but in my opinion it was just not worth the other problems that it caused. With the folding prop would not back up well at all. The prop could barley make power in reverse and when it did make some way it walked to port and made docking nearly impossible. With this, when in the upper revs the prop would cavitate and make quite a bit of racket. My opinion, stay with the fixed blade unless you need that extra 10th of a second a vile to win a club race.

 

[Steve Dion]

Wow, first positive input regarding 2 blade fixed.

This is about the first positive input that I can remember regarding a fixed 2 bladed prop. Regarding Ken's original question, I doubt that a 16" prop would be good for this boat. If Hunter only used a 15" prop as stock there is probably not enough clearance for a 16" unit. I believe that the rule of thumb is that you need about 15% of the diameter for clearance. Improper clearance is one of the factors that cause cavitation and prop walk.When you decide to change props you should always consult with the shop that is selling you the prop. They can and should be responsible for the prop working properly. They should know the product that they are selling and stand behind the propper sizing. If the boat needs to be pulled and the prop needs to be reworked or replaced they should take responsibility for the hauling or for a diver to replace it. This is not to say that you cannot or should not listen to owners that have insite on any potential problems.

 

[Terrance M. Maloney]

Pic of the 15x12 on an H28

Here is a photo of the 15x12 at last haulout.

 

[Kevin]

No Martec ....But

I don't have a Martec but do have a 16x12 Maxprop on my 28.5. No problems with the typical, stuff that comes up when talking props. Excellent control in reverse ( 4 knots), NO prop walk, and its been going strong for 7 years.Kevin