lancing marine prop

hello everyone what is your opinon on on langing marines surface prop i have one of his 17x25s at the moment its heavily raked to give maximum bow lift and seems to have a large blade area but i would like to try something different but all the other props i look at seem to be verry small blade area i bought a 17x26 on ebay and it was thay small the boat would hardly get on plane then when it did get up it was seriousely over reving what do you think cheers gerry....

 

Gerry, You are getting involved in an area where there are not many who can advise you. Most people do not understand surface props at all, and I dont blame them, they work in a different way than a screw.

Many people think for instance that they are only for high speed boats of 40KTS plus and have to be turned at high speed. Well thats how they used to be.

You do not say what boat you have or what drive type, engine etc

The correct thing for you to do is to go and see a prop company, they will tell you what you need and will make one for you. This will be cheaper in the long run than buying every prop off E bay.

However The correct way to have done this would have been to the prop company before you engined the boat. They would have then designed a prop that your boat needs and then told you what RPM and HP Torque ETC that you need to drive it, you then will be left with a choice of engines.

 

thanks for your reply jack o and by the way youl have to excuse all the spelling mistakes and stuff this compuiter stuff is all new to me... you see it all started when i bought a 27ft fletcher zingaro hull and converted it into a fishing boat and bought one of the new 300 mercruiser deisels with a zf63a 1.56-1 and fitted it out with the conventional shaft system / i thought it was going well at 37mph so i entered in a fishing boat race on the lake that i live beside (lough neagh) its a race thats run every year to see who has the fastest fishing boat of course i got walloped by some dude with a 440 yanmar in an old wooden boat doin 40mph.i got that much stick from everyone because i got beat by an old wooden boat i had to bend the rules a little . so one day i spotted this lancing marine drive on boatsandoutboards and decided id give it a go i put it on and rang mike bellamy he suggested a 17x25 i put it on and with a few adjustments the boat went straight to 49.5mph leafil and of course it was pay back time at the race the poor old bloke that just had spent 20k on his 440 yanmar was blinded with my roosters tail it was a 2mile race and i beat him by about 30 boat lenghts happy days but at the same time i will still need to improove for next year cus ye never no what can happen in 12 months so thats why i would like try a different a different prop like a rolla or summit because years ago i was usin bellamys prop with the conventional system and changed to another prop called cambrian i just realised that bellamys prop was crap cheers gerry

 

Sounds like you Mercruiser diesel is the Yanmar 6lpa? Is that right? Gerry it sounds as though you got it right first time. If your pulling MaxRPM then its going as fast as it can. You could try --tweeking a bit but in my experience if it aint broke dont fix it. You have probably got it humming right now. Its an expensive job swopping surface props just to see if its better. I think you would fall over if you saw the price of Rolla's.

 

yea i think your right jack the mercruiser is the vm/motori/detriot www.vmmotori.it just when you say tweek i took the boat out of the water and moved the angle of the prop shaft from 8deg to 3deg and as the engine is the d-tronic version i got a tuning box for it . it just plugs in and gives it 60hp straight away so i priced a new prop off lancing marine 3inc more pitch was 1100 including vat so that might help cheers gerry

 

Gerry I find this ineresting even if not many others do but your a bit vague. You mean you took the boat out of the water and alterd the angle of the shaft by what --altering the engine position? I am assuming that you have a fixed shaft system. I am not familiar with the Lancing marine drive.

You seem to know more than most and doing stuff like this will teach you more. A surface prop runs on the surface --no higher no lower.

I cant help you much but watch your prop slip, by that I mean an increase in prop dia might do more good than pitch. Basically throw the biggest prop you can get on. Now I realise that with drives such as Arneson there is no limit but Arneson say they expect no more than 10% slip if not better-- that raised my eye brows a bit Ille tell yer.

I have a cat with surface drives running Sea fury props ( fixed system 10 degree) I cant get any bigger diam on, consiquently I suffer a tad over 20% slip, I need to go from 24 inch to 26 inch and I dont have the space.

Gerry do you have any pics????

 

yea it is a fixed drive i was using the r&d clamp to couple the shaft to the gear box but i coulden get the engine down any lower as the sump was touching the hull (not good) so i moved the engine forward 6inc and coupled it with a universal joint like ye get on lorry that left me plenty of room under the sump and the shaft angle more horizantal to get more bow lift. I was gettin a lot of slip at the start but i got the prop cupped and thankfully at the mo i dont seem to be gettin any slip i also tried puttin the exhaust out in front of the prop that helps gets the rpm up and it also makes life easier on transmission.I will try and get my wife to get a few pictures sent today cus im not much good at this stuff