Reply
 
Thread Tools Search this Thread
 
Old 13 May 2014, 15:48   #1
Member
 
Nasher's Avatar
 
Country: Other
Town: Principalite d'Chaos
Boat name: The Nashers Revenge!
Make: Ocean & Bombard
Length: 6m +
Engine: Suzi DT200EFI, DT9.9
MMSI: "Mmmmm SI" she said!
Join Date: Jan 2004
Posts: 4,162
380/15HP Prop suggestions

Need to consider what to do about the prop on the Suzuki DT15 I'm rebuilding for our Bombard 380.

The one with the engine is quite rough, with part of a blade missing, but is the std short shaft 9 1/4 x 11.

They come in sizes from 9 1/4 x 8 to 9 1/4 x 11.

What size props are others using on 380s with 15Hp engines?

Thanks

Nasher
__________________

__________________
RIBBED For extra pleasure.
Member of the ebay Blue RIB cover club.
Member of the Bombard 380 Aerotec club
Nasher is offline   Reply With Quote
Old 13 May 2014, 16:58   #2
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider Boats
Length: 4m +
Engine: Tohatsu 18 /30 HP
Join Date: Sep 2007
Posts: 1,706
What's the Bombard max HP rated for ? If 15 is top which would doubt probably will need a prop maximization (play with pitches) to bump up revs.

Will need to test that standard prop with a induction tach and determine if inside min-max safety wot parameters factory stated for that engine to start with.

Then pass to a +,- pitch to be near the max wot parameters. Hard to tell with a prop with issues as won't be able to test it correctly to deliver full engine rpm.

Usually you test standard delivered prop and then go from there maximizing prop pitch to match your needs.

Happy Boating
__________________

__________________
Locozodiac is offline   Reply With Quote
Old 14 May 2014, 02:15   #3
Member
 
Country: UK - England
Town: Sussex
Boat name: Bombard, Y-162
Make: Aerotec 380, Y-Class
Length: 3m +
Engine: Mercury Mariner 15hp
Join Date: Jul 2010
Posts: 2,926
Max on the Aerotec is a 25. I (and I guess 99% of others) just use the standard prop that comes with the 15 (same on the Tohatsu 9.8) on their SIB - consensus is for normal use (ie 1 - 3 up, speed around 16-20 kts), from previous discussions this seems to give the best compromise. On the Mercury/Mariner 15 it's the A12P9 (9" x 9).

Page 13 of the manual here gives the 15 2 strokes prop options:

Boatinfo - Mercury Service Manual for 6-8-9,9-10-15 hp
__________________
Max... is offline   Reply With Quote
Old 15 May 2014, 19:54   #4
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider Boats
Length: 4m +
Engine: Tohatsu 18 /30 HP
Join Date: Sep 2007
Posts: 1,706
You could be lugging a under powered engine at wot without knowing it, specially if running a 15 when the sib needs a 25. You would need to maximize your wot numbers in the event that sib will be used with more than 3 sumo passengers. Sorry, no short cuts on this one, will need a tach, are cheap a must have one

To get the idea. My 430 rib rated for min 30 HP engine is used with a Tohatsu 18 HP which gives at wot 30 rpm less than max factory stated, that's with me alone and lightly loaded rib, if add a extra mate, wot rpm will drop at about middle wot range, if add a thirdd mate rpm will drop to near min rpm which isn't good.

As don't like being on the low extreme of its rpm for long time periods just about lugging the engine, simply dismiss the third mate. This means that can take him for a ride at any other throttle setting except wot.

It's bit silly to change a factory delivered prop for any other as per blind recommendation, checking the owners manual without having even tested the original one.

Happy Boating
__________________
Locozodiac is offline   Reply With Quote
Old 16 May 2014, 16:48   #5
Member
 
Nasher's Avatar
 
Country: Other
Town: Principalite d'Chaos
Boat name: The Nashers Revenge!
Make: Ocean & Bombard
Length: 6m +
Engine: Suzi DT200EFI, DT9.9
MMSI: "Mmmmm SI" she said!
Join Date: Jan 2004
Posts: 4,162
Thanks guys, I know this isn't an easy one.

However, as it stands I don't actually have a good prop, the std size one that came with the engine is knackered, I'll have to TIG weld it and spend a lot of time reshaping it, so I'm on the lookout for another.
While I'm about it, and if I get a choice on the size of a replacement, I'd rather be better informed.

Nasher.
__________________
RIBBED For extra pleasure.
Member of the ebay Blue RIB cover club.
Member of the Bombard 380 Aerotec club
Nasher is offline   Reply With Quote
Old 16 May 2014, 19:55   #6
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider Boats
Length: 4m +
Engine: Tohatsu 18 /30 HP
Join Date: Sep 2007
Posts: 1,706
Ideal is to check wot numbers with original one when new with a tach, then will know if opt for your application or if under or over propped. Much easier to play with pitch props.

Try to get that prop on shape again to work and tach it. If underpropped go for at least one less pitch to bump rpm towards the max wot rpm factory stated for that engine.

Happy Boating
__________________
Locozodiac is offline   Reply With Quote
Old 10 July 2014, 11:20   #7
Member
 
Country: UK - England
Town: Sussex
Boat name: Bombard, Y-162
Make: Aerotec 380, Y-Class
Length: 3m +
Engine: Mercury Mariner 15hp
Join Date: Jul 2010
Posts: 2,926
Nasher - finally got round to doing some runs with the tacho on today.

Mariner 15 with standard factory prop.

Best trim position was 2 and achieved 5750 rpm max at WOT. Touched 19 kts lightly loaded with myself 12 stone and young son around 5 stone.
__________________
Max... is offline   Reply With Quote
Old 28 June 2015, 08:20   #8
Member
 
Country: UK - England
Town: Sussex
Boat name: Bombard, Y-162
Make: Aerotec 380, Y-Class
Length: 3m +
Engine: Mercury Mariner 15hp
Join Date: Jul 2010
Posts: 2,926
Nasher, where did you end up with this one?
__________________
Max... is offline   Reply With Quote
Old 13 March 2019, 13:28   #9
Member
 
Country: UK - England
Town: York
Make: Bombard Aerotec 380
Length: 3m +
Engine: 15hp Mariner 2stroke
Join Date: Jul 2012
Posts: 14
Quote:
Originally Posted by Max... View Post
Nasher - finally got round to doing some runs with the tacho on today.

Mariner 15 with standard factory prop.

Best trim position was 2 and achieved 5750 rpm max at WOT. Touched 19 kts lightly loaded with myself 12 stone and young son around 5 stone.
Hi Max sorry for the thread resurrection! I think I have the same set up as you, A380 plus 2 stroke Mariner 15hp with standard prop. My typical usage is also me plus just my 5 stone son.

Is 5750 rpm the maximum the engine revs to or just the highest you could get it to? If the latter then it seems strange that such a lightly loaded/lightweight boat canít get up to the maximum rpm.

My payload is always going to be around the same so I donít need to compromise. Iíd like something with a slight bias towards top speed but without sacrificing too much acceleration. But from what youíve said above it may be slightly over-propped as standard anyway?
__________________
Kong is offline   Reply With Quote
Old 13 March 2019, 16:54   #10
Member
 
Country: UK - England
Town: East Anglia
Boat name: Nimrod II
Make: Aerotec 380
Length: 3m +
Engine: Mariner 9.9 4-stroke
Join Date: Nov 2007
Posts: 4,411
When I ran the Aerotec/Mercury 15 2-stroke combo with a standard 9" prop I thought it ideal in all circumstances. With one adult plus light passenger (about 7 stone in my case) I thought it super responsive and lively.

If I understand you are thinking of propping down to get more revs on the OB I can't think that will be very noticeable on an already super lively combo when taking off... and would just add to the noise and stress on the OB with revs nearer the maximum.

Something I've noticed with the Aerotec is that top speed isn't its thing compared with some other sibs/boats. I found upping the power by 30% to 20hp only added a couple of kts so don't think you'll find much improvement above the already well suited 9" prop.
__________________

__________________
Fenlander is online now   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 17:57.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.