Rage

By way of back ground, in the Nordic forum, raytart stated that a prop shop recommended removing the diffuser ring from the stock 26P B1 to eliminate the chine walking on his 28' Nordic Heat (with 1.36 gears). The diffuser ring was removed and the prop was also labbed. The chine walking was eliminated but it can not be know for sure if just the diffuser ring removal or that in combination with the labbing or the labbing alone provided the fix. He also mentioned that other props he tried did not chine walk.

I have a 25' Nordic Rage with a labbed 28P B1 turning 5400 engine rpm with 1.5 gears. With a lot of trim at WOT I can get a lot of chine walking and would obviously like to reduce that potential and make the boat more stable if I can.

My question is, does the removal of the diffuser ring from a B1 prop always provide improved resistance to chine walking?

Wardey

Not familular with Nordic's but trim the drive down a click and see if it settles the boat down. You might be surprised to see the boat is faster. Also, hydraulic steering and run the tabs neutral or just below. Dave

Rage

Dave,

Thanks. Yes a little trim back or positive tabs settles the boat right down again but for max mph this hull likes the ragged edge so I am interested in if the noted prop mods would provide the ability to run more trim w/o chine walking.

Wardey

Give Julie at Throttle Up a call...she can answer your prop question. Also, just learn to drive the chine out. Dave

Rage

Thanks for the response. I will continue to work on my driving technigue to control the chine walking. However I am interested to learn if by removing the diffuser ring that will by itself reduce the potential for chine walking. Or to put it another way does the presense of the diffuser ring cause chine walking to occur more readily? I am looking ot optimise my set up for maximum stability. Since I do not have through the prop exhaust I suspect i do not need the diffuser ring to prevent prop blow out. I was hopeing that Trottle Up or other prop experts might chine in on this question.

bbladesprops

With maximun trim angles, trying to gain that little extra rpm and speed, chining is more likely to occur. Certain hulls will also chine worse than others. X dimentions on these hulls alsoplay into the senario.V bottoms and deep X's can be the worse.

Yes, the diffusers can amplify the chining once it begins. The ramping effect the flares have, can fertilize the motion once it begins, especialy if the props are surfaced.

More seat time may allow you to control the chine before it even starts. Preventing, not driving through is the key.

Rage

Your knowledgable response is very much appreciated. Any reason not to have the diffuser rings removed since ny exhaust is through the hull not the prop?

bbladesprops

No reason if the boat gets on plane easily.

We can do it if you need help.

Rage

Could you explain what you are referring to when you say "if the boat gets on plane easily." For example are you referring to prop cavitation during plane out? I assumed the diffuser ring was solely to keep through the hub exhaust from getting to the propellor blades and causing cavitation. Is the diffuser rings also needed to prevent prop cavitation even when there is no through the hub exhaust?

What would it cost to have the diffuser ring removed from a labbed 28P Bravo 1 ?

Rage

bbladesprops?