<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div><span>Mark,</span></div><div style="color: rgb(0, 0, 0); font-size: 12px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span>The first time I read your explanation, I misunderstood, sorry about that, I got it backwards. </span></div><div style="color: rgb(0, 0, 0); font-size: 12px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span>Hank</span></div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12px;"> <div
style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 16px;"> <div dir="ltr"> <font size="2" face="Arial"> On Tuesday, October 28, 2014 8:17 AM, hank pronk via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br> </font> </div> <br><br> <div class="y_msg_container"><div id="yiv0510714642"><div><div style="color: rgb(0, 0, 0); font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12px; background-color: rgb(255, 255, 255);"><div><span>Mark,</span></div><div style="color: rgb(0, 0, 0); font-size: 12px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span>You just made my point. lower bollard pull comes from a lack of power and likely rpm. Sure you can design a sub to have equal bollard pull with jets, but it will have a
much larger energy draw. Big energy draw is bad :-) Also eyeball engineering can work well when backed up with real world experience.</span></div><div style="color: rgb(0, 0, 0); font-size: 12px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span>Hank</span></div> <div class="yiv0510714642qtdSeparateBR"><br clear="none"><br clear="none"></div><div class="yiv0510714642yqt8597132404" id="yiv0510714642yqt88511"><div class="yiv0510714642yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12px;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 16px;"> <div dir="ltr"> <font size="2" face="Arial"> On Tuesday, October 28, 2014 5:44 AM, Marc de Piolenc via Personal_Submersibles
<personal_submersibles@psubs.org> wrote:<br clear="none"> </font> </div> <br clear="none"><br clear="none"> <div class="yiv0510714642y_msg_container">I'll say it again: eyeball engineering doesn't work with ducted <br clear="none">propulsors. The Navy's river patrol boats used in Vietnam had water jet <br clear="none">units built, so I am told, by the Jacuzzi firm, makers of whirlpool <br clear="none">baths! Somebody there must have understood propulsion, though, because <br clear="none">the units worked well.<br clear="none"><br clear="none">A ducted unit optimized for low speed and static operation will achieve <br clear="none">a
mass flow equivalent to a (much) larger open propeller, and will get <br clear="none">better static thrust. Lower bollard pull for the same hp just means the <br clear="none">ducted unit was not correctly designed for the application.<br clear="none"><br clear="none">Best,<br clear="none">Marc<br clear="none">Ducted fans: <a rel="nofollow" shape="rect" target="_blank" href="http://massflow.archivale.com/">http://massflow.archivale.com/</a><br clear="none"><br clear="none">On 10/27/2014 1:35 PM, Phil Nuytten via Personal_Submersibles wrote:<br clear="none">> A quick weigh-n on water jets. Years ago (many) I talked to the pilots<br clear="none">> of the Cousteau “Puce de Mer” (Sea Fleas) And the famous ‘SP 350, Diving<br clear="none">> Saucer’ about the efficiency of their water jet propulsion units. They<br clear="none">> confirmed that they were very ‘weak’ in a comedic way . . .they had a<br clear="none">> phrase in French
which made the two Sea Flea pilots break out laughing –<br clear="none">> my trusty translator also laughed and then tried to keep a straight face<br clear="none">> as he said “they are saying that the things that
you ask about are not<br clear="none">> strong enough to “ pull a penis out of a bucket of lard”!<br clear="none">> Some years later we tried a high volume water pump coupled with a duct<br clear="none">> engineered to work most efficiently with the pump. We hooked it up to a<br clear="none">> fixed pad eye inside our large test tank and used a spring scale to<br clear="none">> determine the bollard pull. Our froggie friends were quite right: using<br clear="none">> a conventional prop powered with exactly the same horsepower gave a<br clear="none">> large increase in bollard pull.<br clear="none">> *From:* Alan James via Personal_Submersibles<br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">> *Sent:* Sunday, October 26, 2014 9:30 PM<br
clear="none">> *To:* Personal Submersibles General Discussion<br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">> *Subject:* Re: [PSUBS-MAILIST] Water jets<br clear="none">> Marc,<br clear="none">> didn't want to have to Google again.<br clear="none">> Wiki.....Classic prop-drives are generally more efficient and economical<br clear="none">> at low speeds, up to about 20 knots (37 km/h; 23 mph), but as boat speed<br clear="none">> increases beyond this, the extra hull<br clear="none">> <<a rel="nofollow" shape="rect" target="_blank" href="http://en.wikipedia.org/wiki/Hull_">http://en.wikipedia.org/wiki/Hull_</a>(watercraft)>resistance generated by<br clear="none">> struts, rudders <<a rel="nofollow" shape="rect" target="_blank"
href="http://en.wikipedia.org/wiki/Rudder">http://en.wikipedia.org/wiki/Rudder</a>>, shafts (etc.)<br clear="none">> means waterjets are more efficient in the 20-50 knot range (up to 90<br clear="none">> km/h; 60 mph).<br clear="none">> Alan<br clear="none">> ------------------------------------------------------------------------<br clear="none">> *From:* Marc de Piolenc via Personal_Submersibles<br clear="none">>
<<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">> *To:* Personal Submersibles General Discussion<br clear="none">> <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">> *Sent:* Monday, October 27, 2014 1:24 PM<br clear="none">> *Subject:* Re: [PSUBS-MAILIST] Water jets<br clear="none">><br clear="none">> A blythe generalization that is essentially meaningless.<br clear="none">><br clear="none">> As Pazmany used to say: poot some nombers to it!<br clear="none">><br clear="none">> Marc<br clear="none">><br clear="none">> On 10/27/2014 3:50 AM, Alan James via Personal_Submersibles wrote:<br clear="none">><br
clear="none">> > Also I did a bit of research on jet propulsion a couple of weeks back<br clear="none">> > & what I read said it was inefficient compared to conventional<br clear="none">> propulsion.<br clear="none">> > Alan<br clear="none">> ><br clear="none">> >
------------------------------------------------------------------------<br clear="none">> > *From:* Alec Smyth via Personal_Submersibles<br clear="none">> > <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>><br clear="none">> > *To:* Personal Submersibles General Discussion<br clear="none">> > <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br clear="none">> <mailto:<a rel="nofollow" shape="rect"
ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>><br clear="none">> > *Sent:* Monday, October 27, 2014 8:11 AM<br clear="none">> > *Subject:* Re: [PSUBS-MAILIST] Water
jets<br clear="none">> ><br clear="none">> > I don't think water jets are necessarily inefficient, but if there is<br clear="none">> > considerable piping around of the water before it exits through the<br clear="none">> > jets, that's what I was referring to. However, even that was not meant<br clear="none">> > as criticism, it is just a normal trade-off. It is surely less efficient<br clear="none">> > than a conventional direct-coupled prop, but you also get<br clear="none">> > entanglement-resistance and maneuverability.<br clear="none">> ><br clear="none">> ><br clear="none">> ><br clear="none">> > On Sun, Oct 26, 2014 at 10:11 AM, Marc de Piolenc via<br clear="none">> > Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank"
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">> > <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>>> wrote:<br clear="none">> ><br clear="none">> > There is nothing inherently inefficient about waterjets. There are<br clear="none">> > commercial fast ferries using
them and getting very good thrust per<br clear="none">> > horsepower - better than any supercavitating propeller could do at<br clear="none">> > the same speed, certainly.<br clear="none">> ><br clear="none">> > Lousy design will of course produce poor results, and jets are much<br clear="none">> > less amenable to rule-of-thumb
construction than open propellers.<br clear="none">> > But whether it is "well known" or not, good design will produce good<br clear="none">> > results.<br clear="none">> ><br clear="none">> > Marc de Piolenc<br clear="none">> ><br clear="none">> > On 10/26/2014 8:41 PM, hank pronk via Personal_Submersibles wrote:<br clear="none">> ><br clear="none">> ><br clear="none">> > Graham,<br clear="none">> > In the world of marine jet drive it is well known that jet drive<br clear="none">> > takes two times the horse power to do the same job. Jet drive<br clear="none">> > is well suited to a craft that needs a shallow draft. I think<br
clear="none">> > you will find it very complicated to control and it will be very<br clear="none">> > inefficient. I
have been down this road, I love the concept but<br clear="none">> > abandoned it. If you go forward may I suggest you start with a<br clear="none">> > jet drive. It is not a simple part to replicate. The impeller<br clear="none">> > tolerances are critical. I have a jet unit on the shelf I could<br clear="none">> > donate to your project. The jet is from a jet ski. I would<br clear="none">> > consider a single rear motor on a full gimbal.<br clear="none">> > Hank ------------------------------__--------------<br clear="none">> > On Sun, 10/26/14, Graham Bayliss via Personal_Submersibles<br clear="none">> > <<a
rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.__org" target="_blank" href="mailto:personal_submersibles@psubs.__org">personal_submersibles@psubs.__org</a><br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.__org" target="_blank" href="mailto:personal_submersibles@psubs.__org">personal_submersibles@psubs.__org</a>><br clear="none">> > <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>>> wrote:<br clear="none">> ><br clear="none">> > Subject: [PSUBS-MAILIST]
(no subject)<br clear="none">> > To: "'Personal Submersibles General Discussion'"<br clear="none">> > <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.__org" target="_blank" href="mailto:personal_submersibles@psubs.__org">personal_submersibles@psubs.__org</a><br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.__org" target="_blank" href="mailto:personal_submersibles@psubs.__org">personal_submersibles@psubs.__org</a>><br clear="none">> > <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br clear="none">> <mailto:<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank"
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>>><br clear="none">> > Received: Sunday, October 26, 2014, 7:39 AM<br clear="none">> ><br clear="none">> > #yiv9417249292<br clear="none">> > #yiv9417249292 --<br clear="none">> ><br clear="none">> > _filtered #yiv9417249292 {panose-1:2 4 5 3 5 4 6 3 2 4;}<br clear="none">> > _filtered #yiv9417249292 {font-family:Calibri;panose-1:__2 15<br clear="none">> > 5 2 2 2 4 3 2 4;}<br clear="none">> > #yiv9417249292<br clear="none">> > #yiv9417249292 p.yiv9417249292MsoNormal,
#yiv9417249292<br clear="none">> > li.yiv9417249292MsoNormal, #yiv9417249292<br clear="none">> > div.yiv9417249292MsoNormal<br clear="none">> > {margin:0cm;margin-bottom:.__0001pt;font-size:12.0pt;}<br clear="none">> > #yiv9417249292 a:link, #yiv9417249292<br clear="none">> > span.yiv9417249292MsoHyperlink<br clear="none">> > {color:blue;text-decoration:__underline;}<br clear="none">> > #yiv9417249292 a:visited, #yiv9417249292<br clear="none">> > span.__yiv9417249292MsoHyperlinkFollo__wed<br clear="none">> > {color:purple;text-decoration:__underline;}<br clear="none">> > #yiv9417249292 span.yiv9417249292EmailStyle17<br clear="none">> > {color:#1F497D;}<br clear="none">> > #yiv9417249292 .yiv9417249292MsoChpDefault<br clear="none">> > {}<br clear="none">> > _filtered #yiv9417249292
{margin:72.0pt 72.0pt 72.0pt<br clear="none">> > 72.0pt;}<br clear="none">> > #yiv9417249292 div.yiv9417249292WordSection1<br clear="none">> > {}<br clear="none">> > #yiv9417249292
Hi I am near the end of my build<br clear="none">> > of my k350 and have started to look at new designs I am<br clear="none">> > interested in building a flyer sub and have come up with a<br clear="none">> > design which will include a vectored motor drive this will<br clear="none">> > enable my flyer to hover and stop where ever I want. I have<br clear="none">> > designed a motor unit which will drive a fan type propeller<br clear="none">> > as an intake this will force water to the rear of the unit<br clear="none">> > where it is compressed then it is forced into ducting<br clear="none">> > which will take the water to four nozzles on the side of<br clear="none">> > the craft. The nozzles are able to turn three hundred and<br clear="none">> > sixty degrees both side are independent of one another so<br
clear="none">> > rolls will be achievable. The reason for a vectored motor is<br clear="none">> > you only need one motor source and one
power pack this will<br clear="none">> > ease the maintenance and increase the enjoyment of using<br clear="none">> > your sub. I am interested in the clubs thought of this kind<br clear="none">> > of design. Graham<br clear="none">> ><br clear="none"><br clear="none"><br clear="none">-- <br clear="none">Archivale catalog: <a rel="nofollow" shape="rect" target="_blank" href="http://www.archivale.com/catalog">http://www.archivale.com/catalog</a><br clear="none">Polymath weblog: <a rel="nofollow" shape="rect" target="_blank" href="http://www.archivale.com/weblog">http://www.archivale.com/weblog</a><br clear="none">Translations (ProZ profile): <a rel="nofollow" shape="rect" target="_blank" href="http://www.proz.com/profile/639380">http://www.proz.com/profile/639380</a><br clear="none">Translations (BeWords profile): <a rel="nofollow" shape="rect" target="_blank"
href="http://www.bewords.com/Marc-dePiolenc">http://www.bewords.com/Marc-dePiolenc</a><br clear="none"><br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" target="_blank" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"><br clear="none"></div> </div> </div> </div></div> </div></div></div><br><div class="yqt8597132404" id="yqt54022">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org"
href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"></div><br><br></div> </div> </div> </div> </div></body></html>