Diablo build and P19 update

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Diablo build and P19 update

Post by grundasaurus » Mon Jul 27, 2020 2:07 pm

Hey all, we've been very busy throughout quarantine building a Bolger Diablo from plans found in a book. Start to finish the build was 3.5 months which was by far the fastest boat we've built. We ended up putting a 60 horse Johnson on it and beefed up the structure considerably. We moved the central frame forward by a foot to have a casting platform on the front, and moved the rear frame back by 8 inches to brace the transom and build in a motor well. We then added three 1x2 frames that tie into the centre console and the longitudinal 1x2 pieces for further stiffening. On the bottom of the boat there is a 3.5" tall skeg that extends forward 8 feet that also acts as a stringer. The transom itself is fully glassed in with biaxial and we added a 3/4" stiffening piece. We opted for a workboat layout with an open rear area where the driver just stands on a slatted deck at the centre console. The boat has a large arch over the engine, with a 100W solar panel that I had laying around, this keeps the battery topped up and helps with fuel economy a bit by reducing the rectifier load on the engine. The boat is scary fast, I've not gotten anywhere close to flat out, the fastest I've seen so far on the gps was 29 knots. The flat bottom can be a little bit of a pain going over boat wakes, and I am now thinking of how I could build a vee onto the narrow flat section off the bottom.

Our P19 Roxanne has been a dream so far over the summer, we've been mostly heading up to the lakes with 6 people on board. Having the long roof is very helpful for strapping paddle boards etc. The fuel economy it achieves is incomprehensible compared to similar production boats. At my last fill up we had added 5 hours of engine time, but only burnt through 15 gallons of fuel. Our P19 also has a 100W solar panel on it, and I would confidently say the fuel economy gains are noticeable to say the least from not having much of an alternator load if ever. the boat has two marine deep cycle batteries, and with the panel I've never seen it below 14.5 volts charging in the day, at night the batteries hover at around 12.8-12.7 volts. This year we added a pair of smart tabs to help add some lift at the stern, this has improved the ride considerably, at the end of the day the boat will never ride like a Grady, but it also doesn't burn 10gph, so the bumpier ride is worth the savings in fuel. The more we run it the more apparent it is that we need to get a slightly coarser prop, the 115 will rev up to 6200 if you let it, and the boat will cruise at 24 knots at 4600 rpm and 33 knots at 5500 rpm, those values are read off the gps.

GV11, several rowboats, P19 in progress

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Re: Diablo build and P19 update

Post by Fuzz » Tue Jul 28, 2020 12:31 am

30 in the Diablo must feel like 60 in a bigger boat. It sure looks like it turned out well.
Good to know the P19 is still working out well for you.

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Re: Diablo build and P19 update

Post by cracked_ribs » Tue Jul 28, 2020 10:42 am

Are there pics of the completed P19 anywhere? I often wondered how that one turned out. I remember you had thoughts about changing the transom around a bit but I can't remember what you decided on.

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