Seafury Marine Surface Propulsion Systems
Seafury Marine Surface Propulsion Systems

Frequently Asked Questions

At Seafury we get asked many questions about surface drives, as it is a technology that a lot of people aren't all that familiar with, and don't quite understand how surface drives operate. We have compiled a list of commonly asked questions that our Senior Designer and original Seafury Founder, Dave Winter, has answered for us. But if you have any questions of your own that have not been answered here, please feel free to contact us.

1. What type of configurations or how many drive units can you use?

As long as there is room on the transom for the propellers and tip clearance, you can use as many as practical.

2. Is surface propulsion suitable for EVERY vessel?

No. It all depends on hull design, weight, speed and several other factors. It is not for every boat, but is suitable for many different vessels.

3. Does it matter how far away the propeller is from the transom?

Yes. You can have them too close which does not give the propellers enough air.

4. Can surface drives be used in conjunction with other propulsion systems?


5. Is the propeller more likely to suffer damage from surface debris?

It would suffer no more and no less damage than that of an underwater propeller.

6. With the hammer effect/chopping style of the propeller, how often do you need to have the propeller re-pitched and how quickly does it lose it's original tuning?

Due to the surface propeller working in a super ventilated environment rather than a cavitating environment, we would see a longer life span than a conventional cavitating propeller.

Our propellers also have what we term as 'initial pitch'. This pitch is set to approximately 4% above maximum boat speed so the prop enters the water very gently. However, the section of the blade is approximately 15% thicker than a conventional blade. This is to take care of the high cyclic loading.

7. Depending on the hull configuration, Arneson adjustment will trim the bow for the best handling and speed performance. How does Seafury overcome the finer adjustments required to squeeze that extra few knots at top speed?

The drive trim will only affect hull trim in a very high speed range where the vessel has very high Horse Power to weight ratio i.e. racing hulls.

8. Why do boat builders/owners want a trimmable drive?

Because that's the way they've been educated. Most naval architects are aware that a trimmable drive system makes little to no difference on the trim of a vessel.

9. What is the top speed going astern and what is the handling at that speed?

I personally have backed down at 10 knots and would have done more, but you have to keep in mind the underwater exhaust and the engines shutting down = water in the engines. However, this can be said for any vessel with exhaust at water line i.e. game boats. The handling was very good at this speed.

10. Is the better astern performance due to the 45° transom, or the propeller, or something else?

It's the specially designed transom that makes the astern performance as good as it is.

11. What is the actual amount of weight that the SF36 could take before it starts to affect the performance?

It is all dependent on water line length and Horse Power.

12. What electrolysis protection do you provide?

Due to the high-grade materials that Seafury Surface Drives are manufactured from (Marine Grade Bronze and High Grade Stainless Steel), they are less susceptible that many competitors units. A lot of other drive systems use Aluminum, which is placed very low down on the Galvanic Series, meaning that they are more affected by sea water.

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