I want to build some boats to take out baited fishing lines a few hundred yards to sea and drop them or use the boat for trolling fishing lures (still attached to shore by line). I will be in the Azores Islands.
I have various .12 -.15 marine and car nitro engines to be run on methanol/castor mix without nitro (too difficult to ship out here). and also various weedcutter engines of 23-26cc ready for converting to aero or boat (have engineering machinery)

Problem is that as an aero man I have no idea about boat props!

Could someone please suggest some props for the small nitros run on straight fuel and also for the weedcutter engines? Speed is not important but reliability, towing power and duration are.

For that purpose you would be better off with an electric set-up rather than IC. Small glow IC are not very good at idling for extanded time. The weedeater option would be better in that respect if equiped with a clutch and air cooling fan, but they require a fairly large prop and off course a bigger boat! Small displacement glow engines don't run well without a least 10% nitro in their fuel

Hello, I was hoping that the small engines might run more reliably with a flywheel but you are probably right.

My present plan-A is actually an RC sailing boat (I have built some 1m class boats before) because it should be able to tow a lure for a very long time before recharging.
While electric would do for just dropping some lines out there and coming back, I don't think batteries would last long enough for a few hours trolling. Like you say, the weedeater is probably better than the small glows.

I think the boat should also have a small sail as a backup and to aid visibility at long distance.

...still wouldn't mind some suggestions for prop sizes and pitches though...

It's is hard to give you prop suggestions when we don't know what size and style of hull you are planning to use. Also your engine will play a large part as well. The combination of these factors will help determine what props. Now you're talking a couple hundred yards you will want a large boat to see what you're doing. Probably a deep vee or a tug boat style hull will be best, but BIG! At that point you're probably better off using a real boat and dropping the line yourself. I'm not against people experimenting and conquering an idea. But I did want to point a few things out. I wish you the best and I hope you keep us posted on any progress, I'll be watching.

I don't want a real boat in the Azores. Anything powered needs a licence because there are no rescue services to speak of. Also I don't want to do Canoe fishing there because I like to stay dry and the biggest Great White ever recorded was caught near our Island.

I'm not after top performance, just a starting point. What props would a .15 powered boat with a draggy hull like? What props for a 26cc gas engine with an equally draggy hull, probably running at half revs most of the time?

BTW. The hull "drag" or equivalent will be A LOT because it will be towing fishing line or lures!

I have no idea where the Azores are, but I understand your situation better now. I wouldn't want to be in a canoe floating around some great whites either! Anyhow most of us in the I.C. section are after speed and are probably hesitant to just throw prop sizes at you. Personally I'm in the habit of propping a boat, not boating a prop. Hope that makes sense, good luck.

I think I'll get a selection of props and just start small/ fine pitch. I suppose it is a bit like asking how long a piece of string is.

Originally Posted by Markx

I think I'll get a selection of props and just start small/ fine pitch. I suppose it is a bit like asking how long a piece of string is.

EXACTLY! If you can afford to buy numerous props (there are MANY to choose from) then go for it. You are working on something that's out of the norm. There's no point in buying more props than you need, but it doesn't hurt to have too many props! I would like to see where this goes....

I want to see how this plays out too. what kind of fish are you trying to catch?

Some of these are pretty expensive but have you looked at a bait boat style to haul a line? They use 12v batts for hours of run time, I don't think gas or glow would be reliable enough then how to you get it back if it dies? The ones with the wireless depth finders are sweet too but lots of $ but maybe you can get some ideas.
12v motors you might be able to salvage from a car wiper motor or the like. Batteries could come from scooters, electric wheelchairs, emergency lighting.
Most of them seem to have jet drive or at least shrouded props to prevent snagging the line.
You might be able to tell what kind of props they are using.
http://www.comparebaitboats.com/
Best of luck catch a cuda for me.

forget a boat, waves too much to handle,

Use a Plane and drop you line anywhere you want!

USMC & Viking...!

Hello Pescador, that's quite a selection of (expensive) baitboats! They all look like they are meant for lake conditions though.
My plan is to
A) bait fish, which means just going out and dropping up to 4 lines in sea conditions.
For rougher conditions I aim to try a heli heading lock gyro.
For safety it could run back along the line instead of dropping the line completely.
Electric would probably be best for that.

B) Troll a lure or deadbait. There are Baracuda and Bonito Tuna here, plus bigger game fish.
For that I am considering electric with sail. A small-medium sail would aid visibility at distance and be good enough to tow a lure for hours without using much battery juice. Having a sail also means there's a backup if the motor fails or the prop gets clogged.


I'll probably go for the low cost approach, IE use gear that's as cheap as possible, because chances are that the thing will head off into the Atlantic solo. I might still do a grp hull for it these though because I used to do moulding for a living and like the idea of easily being able to knock out replacements.

Obviously the prop has to be shrouded and the hull as snag-free as is possible with a keelweight.
I am in GB presently but getting all the bits together for building the boat/s when we move there this year.