Repower my 248 voyager

[Never Enough]

I have a 99- 248 voyager and want to repower. Yamaha is the pref I have a ox66 250 and find that it just doesn't have enough power for me when I weight the boat down for diving, or in rough sea conditions following is even worse. I wanted to put twin f150's but at 475lbs each and the new 300 at 580lbs and the comand link plus it seems which I should do but just seeing if anyone has already. I can't find performance data on my boat with the twin f150's, the Journey is not the same hull so I don't want to use that data and make a $24,000 bad choice.

 

[ocnslr]

We bought our 2002 Islander 270 new in March 2002 with a single 250HP OX66.

Repowered in Oct 2005 with 465hrs on the single. Now have almost 1000hrs on the twin F150s.

Repowered to improve our fuel efficiency sufficiently to fish offshore. The Norfolk Canyon is about 70nm out.

So, what would you like to know?

Brian

 

[wahoo33417]

NE: I think it is likely that your hull design would support the new V6 four-strokes just fine. You can see my post of the new F300 here:
viewtopic.php?f=2&t=15118

I'm pretty sure that Grady can supply the numbers you're looking for. I recall that Yamaha had numbers for the 248 with F115s and 150 HPDIs, but those reports are not on the Yamaha site anymore.

The only difference between the 248 and 258 hulls is that the running bottom is extended through to the transom on the 258. You probably already know that. Grady did this, I'm told, to better support the weight of twin F150s. But since the 248 was available with twin 150 HPDIs, I would think that a single F300 would be fine.

 

[Never Enough]

I guess no one has a repowered voyager? :hmm

 

[Pete1313]

How are you propped with that OX66? I've got the same boat as you, sans hardtop and find the OX66 is great, even loaded down. I had a 4 blade on it, but it was underpropped. Went back closer to stock with a SWS 15 x 17 3 blade and it brought my rpms down to decent range and speed up (cruise, loaded, at 4200 rpms, 26-27 kts GPS calm seas).

I've thought often though about repowering the boat and what I would do. I too want the safety and handling of twins, but I too realized even the lightest twins (zuke 140's) would be 350 lbs heavier than the Yammie on there.

I think with the stepped hull, the only viable choice in terms of weight and buoyancy is a single 300....I just think 825 lbs of motors hanging off the transom would be too heavy on the voyager hull in terms of buoyancy - it'd put your scuppers way below the water line.....but, this is just a guess on my part....so I could be wrong, but have yet to hear of a voyager owner who put twin 4 strokes as a repower....

 

[Never Enough]

what do you do with your boat fish or dive? I do both and with 4 guys and all our crap the boat has trouble getting up. I run a 15.75 x 17 and hit 5200 rpm topping out at 32 knots. I can hardly keep it on plane in sea at 4200. I run it around 4500-4800 cruzing at 24 knots offshore.

 

[Pete1313]

I fish, no diving. Most of my fishing is within local waters (in the islands) and no more than 30 miles from home base.

I misquoted my prop - its a Yamaha SWS I, 15 1/2 x 17M. I bought the boat last year used, and it had a michigan wheel apollo 4 blade on it, 14 5/8 x 16. WAY underpropped. I was cruising with 3 dudes, plus coolers and full fuel at 5200 rpm and 24 kts.

I put the yammie prop on, which is the prop the boat shipped with (confirmed with Grady). My motor no longer sounds like its winding out and that it is under proper load.

It takes me about a second longer to get up on plane, but not an issue for me.

I find if loaded, the boat will start to fall off plane for me around 3700-3800 rpm, depending on condition and location of load.

trim of the motor is a huge factor in my experience. If trimmed all teh way down, I can keep it on plane pretty good, but its not very efficient obviously, because its pushing alot of hull into the water. The above cruise numbers are assuming I've got on plane, in decent water, and can trim it out quite a bit, so just the ass end of the boat is in the water.

EDITED - forgot to say - I too top out around 5200 rpm or so, and hit 35 kts....

 

[Kai Lover]

Like Brian I have a 27 Islander w/twin f150s. I spearfish and the 150s easily handle two divers + gear, 4-6 tanks, plus two other fisherman with gear, 200 gals of fuel, and water tanked off. I am surprised your 250 does not push your 24 better. Sounds like a propping issue. I used to have a 20 overnighter with a F200 and it would also easily pull a full load for diving offshore.

If I were you I would look hard at the new 300. Less weight and new technology. I would not be worried about the reliability issue w/a single unless you really go deep 40 miles +....You will save on fuel, mnx, etc. That would be a nice set up for your rig.