pompebled

Hi Rye,

Your boat looks impressive on the water, congrats!

The bow wave running up to the deck is taking a lot of power, add some sprayrails to deflect the bow wave sideways and the boat will run longer on one charge.

Getting such a large and heavy hull on the plane will require a higher voltage, a couple of 4S Lipo's should do the trick.

Regards, Jan.

rye

My Feedback: (10)

hey she looks good so far mine took a hit last week didnt see the log under the water some one throw a log they wanted to put out from there fire pit and it was just under the top so i didnt see it got some hull damage and props are bended got her home going to fix her this winter since the summer place closes in 3 weeks, where did you get your hull from ? thanks rye

Boulderboater

Hi Jan,
I think you are right about using higher voltage. I have 2 of the 700BB 12V(!) motors, and power each with 18 NiMH cells. About 24V when charged. The Electronizer controllers are rated at 24V/30A each, so hopefully that should do the trick! I expect the motors to get hot, so I put in water cooling coils and 2 pumps. Paul

Boulderboater

Ooh! That must have hurt! I guess you use metal props? I am starting with cheap "plastic" ones until I find the right size. I never thought about them taking a hit - maybe I'll stay with plastic and replace them after impact!
I got the hull at an estate sale, and never found out where it was from. It is quite heavy with almost no internal framing, so I had plenty of room for batteries, etc.
Here are 2 more pics - I can't upload more than 2 and don't know how to reduce the file size, Regards, Paul

rye

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het
it looks like a http://www.franksmosquitoboathobbies.com/pt109.htm good luck please let me know how it turns out and the props you are happy with and run time thanks rye

rye

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look at the bottom of the page http://www.franksmosquitoboathobbies.com/fittings.htm

nicolau

Hey Rye, my name is Jose. I just stumble with the blog of boats. I have an old pt boat with two 108 glow motors, they are in bad shape rebuilding them is out. I would like to go electric since is a lot cleaner and I could lower the boat from myne,then go. Could I still use the same props the are 2.5 inch diameter dont know the pitch. I need help in setting this up. I have been modelingplanesfor over 35 yrs. scale, big,/ small, 3D, pilon racers, ect. Idont' know diddelly do about rcboats, eccept for mine and the maint and care is done by the people at the marina where is kept.
I need help.. please.Where can I get really fast motor and what type of sppeed controllers with reverse should I get?
Thanks in advance Jose

Boulderboater

Hi Jose, what size is your PT boat? 2.5inch props sound rather big!

rye

My Feedback: (10)

no i use 1.25 three blades or 1.50 the bigger the props and it makes it spin out or cavatade i think that the spelling anyways i when with small props and got more run time with the bigger props the bow gets out of the water looks cool but lose run time they dig a hole in the rear of the boat and large wakes here my you tube ptboat84 look for the pt shots thanks rye

nicolau

Ok! Where can I get the 1.5 3 blade props? what pitch should I try? should I go first with plastic, then brass or stainless?. Need to be walked by the hand.. SORY I'm ignorant ab0ut this part of the Hobby.
Thank for your Help.
Jose

nicolau

Did not finished your reply. It is a 48" FG Dumas. Thinking of coppying and make one 8 ft long. First I have to learn withthis one. You know, crawl/walk/run, thanks.
Jose

rye

My Feedback: (10)

as u i am dumb to the prop talk i just try diffenet ones and i think i am still over prop ask these guys
http://www.rossisales.com/octura.html
as for a 8' pt u may have to use a tolling motor look up large pt boats in the forum i think i saw one years ago ,rye

nicolau

Hey, I really like Pauls set-up, I am starting today to clean (removeout what is inside) as much as I can. I will use servoesfrom a3D plane.I don't know how much strees the rudders wouldcreate.Would I need one or two servos for the rudders?.
I have been almost all day going throug this forum and the more I see the more I like.
Mine is not 60" but it will be a learning experience for me, then I can build just like the real ones build-up full scale.
Maybe an80 inches a 1'=1" ,I just retired and have too much time in my hands.
Thanks, Jose

rye

My Feedback: (10)

i build bigger rudders and run them on one servo it made a big diffenets i when 25% more then the plans

Boulderboater

Hi Jose,
I am using 2inch 2blade props with 2 700BB motors, powered up to 22volts. The only way I know to optimize prop size, etc. is trial and error, using cheap plastic props first.
If props are too small, they will rev well at low current, but not make much speed.
If props are too big, they will rev slower and current will rise a lot!!
Look at motor spec. - if best efficiency is, say 15A, put in 15A fuses - then accelerate slowly to max speed. Fuse should not blow.
Then accelerate more quickly - fuses should blow! Now you have got it right, put in bigger fuses, and have fun!
If you don't have a way of recovering boat when fuses blow, then just use one at 15A and one at 30A, then you can limp home on one motor!

rye

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hey me two i just retied i am building rc planes, boats having fun ,rye

Boulderboater

Hi Jose,
I am recently retired, so I know how you feel.
But the problem is not too much time on your hands, as too little muscle in your arms! Remember, double the size of a model means 8 times the weight!!!!
A 4ft model at 20pounds means an 8 footer at 160 pounds!!!!! A 5footer at 30 plus pounds is as heavey as I want to haul around. I have a battleship at about 40pound and a tugboat at 80pound, and they rarely see the water unless I can get help.
Paul

nicolau

OK, Paul. what is the name or type of speed controller u used, water pumps, where did you bought the motors, ect. Need this info so I can start ordering ASAP.
Thanks, Jose

nicolau

OH!! Dum me I just realise that!!. WEIGHT!!! my back is badDDD, even 30 lds might be too much. Another of my reason to quit flying can't walk too far,have to depend on others to help me takethe planes out of the truck, then Can't bend to start the engine, ect.

Boulderboater

Jose, the most important thing, I found, was to cool the motors - the controllers dissipate far less power. The copper coils around the motors don't do much good - the contact area is too small. The coils stay cool, but the motors are still hot!
I have replaced them with the blue jelly type jackets that are in close contact with the motor case. These are as good as it gets, I think, unless you go with full metal jacket, much more expensive.
The amount of pumping needed is actually very small, most pumps over do it, and the water is still cold on exit. I use very small pumps, and so far, have found them OK, water is still coming out, not steam!!
I got the pumps for about $8, in the form of executive table fountains, run on 3 AA batteries. I just smashed the fountain to pieces, recoverd the pumps, and run them off 5v. Perfect!
The 700BB motors are Graupner #6317, from Harbor Models, jackets are gnd-4198 and mounts are grp-2317 ( taller, so the motor fits with jacket on) both from OffShore Electrics. I use Electronize controllers, as the are rated at 24V and 30A, in both directions, without heatsinks! (I can't find how to add pics anymore)
Paul

nicolau

Thanks, thanks Paul
Jose

Boulderboater

I forgot:
the fountains I used were "hand in hand", from Amazon, $7.95, the top breaks off from the base which holds the pump and other stuff. THey used a hot glue gun to assemble it, so it breaks apart easily. Mount them below water level, so they fill when you put the boat in the water, then switch on 5V and they run. Very quiet and very small current - I think about 35mA.Pics show maiden voyage and pump location.
regards, Paul

nicolau

Paul,
I do really appreciate your help.
I just got off the phone with a old friend, His livelihood is to make molds for fiberglass He is an artist. I asked him about making me a mold of a pt boat 60 inches,I would need a blue print, so He canstudy and estimate howmuch willcost Him inmaterials andtime, He is willing to make the plug for the mold. If anyone is interested???? l can have him make a few. I have to see where I can get blu-prints for the elco 80 footer.
Jose

rye

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hey jose
this is the guy i got my plans from i would like a glass hull the wood one i made is really heavy would like to lite it up thanks rye

[email protected]

Boulderboater

Hi Jose,
I have PT-109 plans for 30 inch, that could be enlarged x2, that include the hull lines/stations, will try to upload pics. Also have 60 inch drawings for PT-330, but no hull lines. Any use?? I have a friend who could probably use a FG hull at 60inch, if you get a bunch made.
Paul