Well that's been exciting. My PC has made itself unobtainable, so I'm working on a not very powerful android tablet, fine for doing the crossword, as I seem to make fewer mistakes, but a bit of a trial when writing up the blog, I can't copy the clues directly as is my wont, and am limited to LJ's HTML editor, which thankfully is OK even for me.
As for the crossword, 22.49 which felt a bit slow, with the top half resisting more than the bottom. I wondered if there might be something of a theme with both the triangle word and its most famous exponent, but I think not.
I have done my best to eliminate mistakes and present clues, definitions and SOLUTIONS in my customary style, but if misprings have slipped through, please be kind as you usually are.
1 Projection to get extremely large ratings here (10)
FORECASTLE So projection is FORECAST, to which you add the extreme (letters) of LargE. Your ratings are of course the people shaped navy ones.
6 Stream in gorge to the west (4)
FLOW Gorge here is to eat greedily, or WOLF. "To the west" means you reverse it.
9 Liberal is firm and very devout (7)
COPIOUS Firm is CO(mpany) and very devout PIOUS.
10 Changing ends of meandering route, one wants good fare (7)
GOURMET An anagram (changing), for which you want the letters of ROUTE plus the M and the G from either end of meandering.
12 Date and I loved dancing and were a good match (10)
DOVETAILED And immediately our second anagram (dancing) of DATE and I LOVED.
13 Fighting men cut by a blade (3)
OAR Of the many abbreviations for military personnel, you need OR (Other Ranks). Cut them down the middle with the A in plain sight.
15 When one's getting on with female penning graffito (6)
DOTAGE The female in question is a deer one, a DOE, and the graffito penned thereby a TAG, one of those almost always illegible stylised signatures defacing public surfaces.
16 Distance Parisian is to roam (8)
ESTRANGE The Parisian version of is is EST, to which you add RANGE for roam. Distance here is a verb, not a noun.
18 Possibly getting a raise in pounds provided by board (8)
LIFTABLE Pounds gives you just the single L, or £, provided is IF and board TABLE.
20 Trims twirling officer's coat decoratively (6)
STUCCO So it's to coat decoratively, made up of CUTS for trims, which you twirl or reverse, plus an officer, in this case a CO.
23 Book suppressing final character's age (3)
ERA The book is EZRA from the OT, from which you remove the final character, in my alphabet the Z.
24 Needle with point around figure's side (10)
HYPOTENUSE The way I have this is that we have HYPO for needle of the kind they've recently jabbed in your arm, then USE is from point as in "what's the use/point of doing crosswords" surrounding TEN as a random figure.
26 Help when presenting US car line on the radio (7)
AUTOCUE An American car is an AUTO, and QUEUE for line sounds like CUE where heard on the radio.
27 American peak with worse weather (7)
RAINIER A volcano in the Cascades in Washington State. It helped that the weather here has just turned from dry to soaking, so it's rainier, worse unless welcome for the garden.
28 Herb around old French bread now (4)
EURO The herb is RUE, for remembrance according to Ophelia. It's around, or reversed, and O(ld) is stuck on the end. Bread, of course, slang for money.
29 Philosopher, on leaving, snakes around market (10)
PYTHAGORAS The snakes are PYTHONS, from which ON leaves. They then circle the AGORA, Greek for market, known to you from agoraphobia. The wordplay kindly prevents you spelling P. with a U at the end.
1 Reality about to get inverted in newspaper (4)
FACT C(irc)A for about gets inverted inside the F(inancial) T(imes).
2 Harmony left following musical style (7)
RAPPORT Left supplies you with PORT to follow RAP which is allegedly a musical style.
3 Work with nothing explicit about ballet, say (13)
CHOREOGRAPHIC Work is CHORE, nothing is 0, and explicit GRAPHIC.
4 Strut surely has wood in for example (6)
SASHAY This confused me, because I thought surely (ay perhaps), was part of the wordplay, but I think it's part of the definition as marked. So it's ASH, random wood, surrounded by SAY for for example. Chambers has "to walk or move in a gliding or ostentatious way": that'll do.
5 Bar's words from member with drinks on tab (8)
LEGALESE (Bodily) member is LEG, drinks ALES and your tab(let?) is the E.
7 Bird, catching bit of current, is to take off (7)
LAMPOON The bird is a LOON, and the bit of current it catches is represented by AMP.
8 A new merlot's drunk - it's sweet and refreshing (10)
WATERMELON About time we had another anagram (drunk), here of A NEW MERLOT. Oenophiles of this parish can confirm whether Merlot meets that description.
11 Getting this could be seen as infra dig (13)
UNDERSTANDING I'm going to leave the definition as marked, though dig also has similar overtones. I think the wordplay invites us to think of where we would be if infra, under. I'm happy to be further enlightened.
14 Corrupt? Oddly they're overwhelmed by praise (10)
ADULTERATE Take the odd letters of ThEy'Re and overwhelm them (well, surround them) with ADULATE for praise.
17 Like a shoe, perhaps, that's unsafe to walk on (8)
SLIPPERY The Uxbridge English Dictionary puts in an appearance. Under slippery, it has "a bit like a shoe".
19 Large heavier clothes more streamlined (7)
FLATTER Heavier translates to FATTER, which "clothes", L(arge)
21 One handling money in his care roughly (7)
CASHIER Another anagram (roughly), of HIS CARE.
22 Formality which may come from King Edward (6)
STARCH I believe starch is a major component of the potato, of which King Edward is an example.
25 Most of national flag (4)
IRIS The national you need is IRISH. Lose the last letter.